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Higher viscosity = higher operating temps?

Posted By: 2015_PSD

Higher viscosity = higher operating temps? - 09/06/19 01:15 AM

Has anyone seen an oil temperature increase by moving from say an xW-20 to an xW-40 (with everything remaining the same)?
Posted By: Shannow

Re: Higher viscosity = higher operating temps? - 09/06/19 02:50 AM

Yep,
5W20 to 25W60 in my Briggs and Straton makes quite a difference.

That was an air cooled engine, so you won't see a coolant temperature change.

My old J-Car, lost a few MPG going SAE30 to 25W70...that's ALL oil related heat.
Posted By: JLTD

Re: Higher viscosity = higher operating temps? - 09/06/19 03:29 AM

I went from 5w-20 to 0w-40 (with 5w-30 in between) in my 2013 F150 (5.0), with no discernible difference in mpg or power.

I imagine going to a 70 (! dang Shannow) might have made a difference....there's thick, then there's TOO thick.
Posted By: Mad_Hatter

Re: Higher viscosity = higher operating temps? - 09/06/19 04:53 AM

Originally Posted by 2015_PSD
Has anyone seen an oil temperature increase by moving from say an xW-20 to an xW-40 (with everything remaining the same)?

I'd say the new Xw-40 lube isn't moving as freely (reduced flow) throughout the engine, as compared to the previous Xw20 lube? You would get more heat if the oil film weren't as thick as the previous lube but I would expect that to happen (potentially) if you went down in viscosity, not up.

I suppose it's possible to see a noticeable rise in oil temp related to oil drag..too thick of an oil can actually increase wear (rate) on some components.
Posted By: RDY4WAR

Re: Higher viscosity = higher operating temps? - 09/06/19 05:09 AM

Yes. Street stock engines running 5000-7000 rpm sustained at near WOT the entire time. On 20w-50, the oil temp hangs around 280*F. On 10w-30, it never tops 260*F.

In my own car, sticking with 5w-30 all year around produced the same 220-230*F oil temps all year around. Going to 5w-40 in the summer increased temps to near 240*F.
Posted By: paulri

Re: Higher viscosity = higher operating temps? - 09/06/19 06:50 AM

Interesting question. Since the answer appears to be yes, then why is this the case? Is it that the engine has to work harder, to push through a thicker oil? Or is it that a thicker oil will absorb heat better? If I understand Mad Hatter correctly, he is saying that it is the first--that the engine has to work harder?

Originally Posted by Mad_Hatter
I suppose it's possible to see a noticeable rise in oil temp related to oil drag..too thick of an oil can actually increase wear (rate) on some components.
Posted By: Silk

Re: Higher viscosity = higher operating temps? - 09/06/19 06:54 AM

Originally Posted by JLTD
I went from 5w-20 to 0w-40 (with 5w-30 in between) in my 2013 F150 (5.0), with no discernible difference in mpg or power.

I imagine going to a 70 (! dang Shannow) might have made a difference....there's thick, then there's TOO thick.


Currently have 15W-60 in my Volvo, and no noticeable in crease in temp or fuel consumption...that's just using a temp gun on the sump, and it has a heat exchanger in the top tank, so basically running at coolant temp. In fact my best ever fuel consumption has been done on the 15W-60 - 7 litres per 100km for 100km open road...33.6 mpgUS., 40mpg UK.
Posted By: zeng

Re: Higher viscosity = higher operating temps? - 09/06/19 07:26 AM

It's rpm driven under light load condition , IMHO.
Posted By: FordCapriDriver

Re: Higher viscosity = higher operating temps? - 09/06/19 07:57 AM

Originally Posted by Silk
Originally Posted by JLTD
I went from 5w-20 to 0w-40 (with 5w-30 in between) in my 2013 F150 (5.0), with no discernible difference in mpg or power.

I imagine going to a 70 (! dang Shannow) might have made a difference....there's thick, then there's TOO thick.


Currently have 15W-60 in my Volvo, and no noticeable in crease in temp or fuel consumption...that's just using a temp gun on the sump, and it has a heat exchanger in the top tank, so basically running at coolant temp. In fact my best ever fuel consumption has been done on the 15W-60 - 7 litres per 100km for 100km open road...33.6 mpgUS., 40mpg UK.


Wish i could get Penrite in Spain, specially some HPR30 20W-60...
Just the thought of that lovely bright stock base with 1600ppm of ZDDP makes my mouth water slobber
Posted By: Silk

Re: Higher viscosity = higher operating temps? - 09/06/19 08:15 AM

Originally Posted by zeng
It's rpm driven under light load condition , IMHO.


No one achieves best fuel economy at max revs and wide open throttle...max manifold vacuum is best. But I never got better economy with lighter oils in the same conditions. And as they say - ''Your results may differ.''
Posted By: Mad_Hatter

Re: Higher viscosity = higher operating temps? - 09/06/19 08:18 AM

Originally Posted by paulri
Interesting question. Since the answer appears to be yes, then why is this the case? Is it that the engine has to work harder, to push through a thicker oil? Or is it that a thicker oil will absorb heat better? If I understand Mad Hatter correctly, he is saying that it is the first--that the engine has to work harder?

Tolerances determine the ideal viscosity..too thick of an oil and starvation and drag (resistance) can be a problem; too thin of an oil and oil film thickness can become an issue in preventing metal to metal contact.

The thicker the oil, the harder the engine has to work to push that oil through the engine, filter etc. This (engine working harder) will cause an increase, on some level, of engine temps. This is also why high viscosity oils are not designated resource conserving (increased fuel consumption). In addition, higher viscosity oils have larger molecules and when an oil ages and the lighter molecules burn off you have a high(er) concentration of those larger molecules (think sludge) that can cause wear in areas of tight tolerance (think bearings). Now synthetics are designed to have uniform molecules that better withstand thermal breakdown as compared to mineral oil. The higher the quality of the synthetic base oil, the more uniform the molecules are and better thermal stability. I believe that the same holds for the type and quality of the viscosity modifiers used.

I'm just a regular Joe trying to relate stuff I've read, so if I've got something wrong please chime in.

There's a lot out there on oil drag but here's some stuff that you might find useful..

Viscosity

Viscosity 2
Posted By: Silk

Re: Higher viscosity = higher operating temps? - 09/06/19 10:22 AM

Oh, so that's all good then, my 15W-60 is ester POA and the uniform molecules are what give me the better fuel economy.
Posted By: Mad_Hatter

Re: Higher viscosity = higher operating temps? - 09/06/19 10:34 AM

Originally Posted by Silk
Oh, so that's all good then, my 15W-60 is ester POA and the uniform molecules are what give me the better fuel economy.

Or even if you're running a grp2 oil, just don't push it past it's break point...oil that's breaking down is going to increase the operating temp and rob your engine of hp, fuel efficiency and increase wear rate.
Posted By: Shannow

Re: Higher viscosity = higher operating temps? - 09/06/19 10:51 AM

Originally Posted by paulri
Interesting question. Since the answer appears to be yes, then why is this the case? Is it that the engine has to work harder, to push through a thicker oil? Or is it that a thicker oil will absorb heat better? If I understand Mad Hatter correctly, he is saying that it is the first--that the engine has to work harder?

Originally Posted by Mad_Hatter
I suppose it's possible to see a noticeable rise in oil temp related to oil drag..too thick of an oil can actually increase wear (rate) on some components.



People get enamoured with the pumping and "flow"...that' not it. Pumping is less than turning on your headlights.

The real losses are in viscous drag in the bearings (and bearing surfaces like piston rings)...in fact, some OTR engine designs of the future will include thermal barrier coatings in the mid stroke area to artificially reduce the viscosity in the mid stroke region.
Posted By: Virtus_Probi

Re: Higher viscosity = higher operating temps? - 09/06/19 11:16 AM

I keep the oil temp up on my MFD and I definitely noticed an increase in temps the first time I used a higher HTHS 5W30 (M1 ESP Formula, HTHS was 3.58 compared to the vanilla M1 5W30 I had been using at 3.1). I don't remember the exact temp ranges anymore, but I think I posted at the time that they went up 5-10F with the ESP.
Since I was used to seeing fairly consistent temp ranges with some dependence upon the seasons (typically a bit cooler in the winter) over some tens of thousands of miles and I made this change in the summer, I was pretty alarmed to see the temp range move up all of a sudden. I actually posted a panicky thread about it on subaruforester.org and some knowledgeable folks there let me know that was exactly what was to be expected...more viscous oil, higher oil temps.
Posted By: ChrisD46

Re: Higher viscosity = higher operating temps? - 09/06/19 02:03 PM

The answer for most people is to equally mix mix 5W20 / 5W30 oil of the same type and manufacturer - theoretically the best of both worlds for oil film thickness and flow to tighter tolerance engine parts and keep OCI's of less than 5K miles.
Posted By: CR94

Re: Higher viscosity = higher operating temps? - 09/06/19 04:53 PM

Originally Posted by ChrisD46
The answer for most people is to equally mix mix 5W20 / 5W30 oil of the same type and manufacturer - theoretically the best of both worlds for oil film thickness and flow to tighter tolerance engine parts and keep OCI's of less than 5K miles.
So the 5W-30 part maintains a thick film, while the 5W-20 part reaches out into "tighter tolerance engine parts" where only it can fit?
Posted By: DGXR

Re: Higher viscosity = higher operating temps? - 09/06/19 07:44 PM

Thicker oil usually generates higher oil pressure, and since physics tells me that higher pressures equal higher temperatures, yes I can see a thicker oil leading to higher oil temps. Not to mention the engine is working harder to pump the thicker oil, generating more heat. And other things mentioned above. Makes sense to me.
Posted By: ka9mnx

Re: Higher viscosity = higher operating temps? - 09/06/19 07:53 PM

Originally Posted by Shannow
...in fact, some OTR engine designs of the future will include thermal barrier coatings in the mid stroke area to artificially reduce the viscosity in the mid stroke region.

Is that possible with the speed the piston moves through that area?
Posted By: Shannow

Re: Higher viscosity = higher operating temps? - 09/07/19 12:22 AM

Originally Posted by ka9mnx
Originally Posted by Shannow
...in fact, some OTR engine designs of the future will include thermal barrier coatings in the mid stroke area to artificially reduce the viscosity in the mid stroke region.

Is that possible with the speed the piston moves through that area?


Certainly is...it's the speed of the piston moving through the area that makes it attractive
https://core.ac.uk/download/pdf/9591723.pdf
Posted By: ka9mnx

Re: Higher viscosity = higher operating temps? - 09/07/19 12:43 PM

Thanks for the link. Now I've got some reading to do!
Posted By: 2015_PSD

Re: Higher viscosity = higher operating temps? - 09/07/19 01:38 PM

I saw a 10°F minimum temperature delta from 0W-20 to 0W-40 and wanted to see if my situation was unique or it was expected. There are always trade-offs and compromises between viscosities and one thing that stuck out for me was at what point is the increased temperature a detriment over the benefit of high viscosity oil.
Posted By: 3311

Re: Higher viscosity = higher operating temps? - 09/07/19 05:40 PM

IMO I doubt seriously if an end user would be able to discern the the difference. Just to many variables.

Now in controlled lab setting it would be possible measure the slight variation in temps.
Posted By: Mad_Hatter

Re: Higher viscosity = higher operating temps? - 09/07/19 10:47 PM

Originally Posted by 2015_PSD
I saw a 10°F minimum temperature delta from 0W-20 to 0W-40 and wanted to see if my situation was unique or it was expected. There are always trade-offs and compromises between viscosities and one thing that stuck out for me was at what point is the increased temperature a detriment over the benefit of high viscosity oil.

I personally wouldn't lose any sleep over it so long as engine temps are still in normal range. But if you were inclined to, you could hunt down the lowest noack Xw40 you could find to appease any concerns about evaporative loss...but then it's a ROI question, isn't it? Watch your dipstick levels on the Xw40..if you're not having to top off more than you normally do, then I'd say the diff' is a non starter. Just my 2 pennies...
Posted By: cb4017

Re: Higher viscosity = higher operating temps? - 09/10/19 04:52 AM

Originally Posted by 2015_PSD
I saw a 10°F minimum temperature delta from 0W-20 to 0W-40 and wanted to see if my situation was unique or it was expected. There are always trade-offs and compromises between viscosities and one thing that stuck out for me was at what point is the increased temperature a detriment over the benefit of high viscosity oil.


Was this in your Rubicon? I'm thinking of going to a 5w-30 in my 2019 Wrangler (3.6L). Off road and while towing my camper I've seen oil temps hit 240. I'm a little skeptical about thin oil holding up.
Posted By: 2015_PSD

Re: Higher viscosity = higher operating temps? - 09/10/19 11:11 AM

Originally Posted by cb4017
Originally Posted by 2015_PSD
I saw a 10°F minimum temperature delta from 0W-20 to 0W-40 and wanted to see if my situation was unique or it was expected. There are always trade-offs and compromises between viscosities and one thing that stuck out for me was at what point is the increased temperature a detriment over the benefit of high viscosity oil.
Was this in your Rubicon? I'm thinking of going to a 5w-30 in my 2019 Wrangler (3.6L). Off road and while towing my camper I've seen oil temps hit 240. I'm a little skeptical about thin oil holding up.
Yes; and I have since swapped back and forth from 0W-20 to 0W-40 and back to 0W-20 and have seen similar temperatures from each viscosity--though the 0W-40 will go a little higher (2-4°F). This engine seems to run at higher temperatures than what I am used to seeing, but from what I see on the Jeep forums, it is pretty normal (cannot say that I like it though). The 3.6L Pentastar was originally specified to run 5W-30 and was used in other countries until 2019 when 0W-20 was specified and at this point all countries specify 0W-20. With that said, I would have no issues running 5W-30 in it and I will likely continue with 0W-40 as I have a large stash of it from my AMG.
Posted By: demarpaint

Re: Higher viscosity = higher operating temps? - 09/10/19 12:22 PM

Originally Posted by 2015_PSD
Originally Posted by cb4017
Originally Posted by 2015_PSD
I saw a 10°F minimum temperature delta from 0W-20 to 0W-40 and wanted to see if my situation was unique or it was expected. There are always trade-offs and compromises between viscosities and one thing that stuck out for me was at what point is the increased temperature a detriment over the benefit of high viscosity oil.
Was this in your Rubicon? I'm thinking of going to a 5w-30 in my 2019 Wrangler (3.6L). Off road and while towing my camper I've seen oil temps hit 240. I'm a little skeptical about thin oil holding up.
Yes; and I have since swapped back and forth from 0W-20 to 0W-40 and back to 0W-20 and have seen similar temperatures from each viscosity--though the 0W-40 will go a little higher (2-4°F). This engine seems to run at higher temperatures than what I am used to seeing, but from what I see on the Jeep forums, it is pretty normal (cannot say that I like it though). The 3.6L Pentastar was originally specified to run 5W-30 and was used in other countries until 2019 when 0W-20 was specified and at this point all countries specify 0W-20. With that said, I would have no issues running 5W-30 in it and I will likely continue with 0W-40 as I have a large stash of it from my AMG.

I'm run currently running 0W30 in my 2016 Rubicon, previously 5W30. I see no noticeable difference in temps from the spec 5W20.

I do agree they run hot, a lot hotter than I'm used to seeing.
Posted By: zeng

Re: Higher viscosity = higher operating temps? - 09/10/19 12:28 PM

Originally Posted by 2015_PSD
I saw a 10°F minimum temperature delta from 0W-20 to 0W-40 and wanted to see if my situation was unique or it was expected. There are always trade-offs and compromises between viscosities and one thing that stuck out for me was at what point is the increased temperature a detriment over the benefit of high viscosity oil.


Originally Posted by 2015_PSD
Yes; and I have since swapped back and forth from 0W-20 to 0W-40 and back to 0W-20 and have seen similar temperatures from each viscosity--though the 0W-40 will go a little higher (2-4°F). This engine seems to run at higher temperatures than what I am used to seeing, but from what I see on the Jeep forums, it is pretty normal (cannot say that I like it though). The 3.6L Pentastar was originally specified to run 5W-30 and was used in other countries until 2019 when 0W-20 was specified and at this point all countries specify 0W-20. With that said, I would have no issues running 5W-30 in it and I will likely continue with 0W-40 as I have a large stash of it from my AMG.

For a 0Wx0 full synthetic oil , I won't be bothered with operating temperature range of 80*C (180*F) and 105*C (220*F) in the context of temperature-driven 'accelerated' oil oxidation.
Instead a thicker oil in 0W40 'gains' higher MOFT over a thinner oil in 0W20 or 0W30 at no additional purchase cost , in fact lower cost in my market .
Posted By: alarmguy

Re: Higher viscosity = higher operating temps? - 09/10/19 12:37 PM

I have agreed for a long time on the bearing thing but here is why, just found this,

"Too thick oil, wonderful oil pressure, yet parts inside the engine could actually be starved for oil due to lowered volume. Another downer, circulating oil accounts for nearly 50% of engine cooling, so reduced oil-flow reduces cooling causing lubricated parts to operate at higher temperatures. Higher parts temperatures, more wear."

Source, Click here

I do know for a fact (menaing have seen photos) that in many motorycycle transmissions where the person ran a heavy weight gear oil, the transmission bearings were very dark color to black which would indicate heat. Mind you, this is not the reason the transmission was being serviced, just an observation by a technician who took photos on many blackened bearings over time.
Posted By: gfh77665

Re: Higher viscosity = higher operating temps? - 09/10/19 12:51 PM

Your 5w-30 ends up being a 5w-20 before you change it anyway...
Posted By: demarpaint

Re: Higher viscosity = higher operating temps? - 09/10/19 12:53 PM

Originally Posted by gfh77665
Your 5w-30 ends up being a 5w-20 before you change it anyway...

According to the UOAs I had done mine hasn't.
Posted By: rooflessVW

Re: Higher viscosity = higher operating temps? - 09/10/19 12:54 PM

Originally Posted by demarpaint
Originally Posted by gfh77665
Your 5w-30 ends up being a 5w-20 before you change it anyway...

Mine hasn't.

It's a ridiculous argument anyway. If a 30 shears down, then a 20 will too.
Posted By: ChrisD46

Re: Higher viscosity = higher operating temps? - 09/10/19 12:56 PM

*Does the Rubicon OM list additional approved oil viscosities - or just the one ? In my Hyundai/Kia the OM lists 5W20 , 5W30 or 10W30 as being allowed - with the caveat that oil viscosity should be chosen based on the anticipated ambient temps during the upcoming OCI . I take this Hyundai/Kia statement to read : "While 5W20 is acceptable - 5W30 or 10W30 will provide more engine protection during the summer months" .
Posted By: CT8

Re: Higher viscosity = higher operating temps? - 09/10/19 12:57 PM

Originally Posted by CR94
Originally Posted by ChrisD46
The answer for most people is to equally mix mix 5W20 / 5W30 oil of the same type and manufacturer - theoretically the best of both worlds for oil film thickness and flow to tighter tolerance engine parts and keep OCI's of less than 5K miles.
So the 5W-30 part maintains a thick film, while the 5W-20 part reaches out into "tighter tolerance engine parts" where only it can fit?

What parts in an engine have a clearance so tight [ tolerance is the allowed variance of the clearance ] that only a 20 wt will reach?
Posted By: CT8

Re: Higher viscosity = higher operating temps? - 09/10/19 12:59 PM

Originally Posted by DGXR
Thicker oil usually generates higher oil pressure, and since physics tells me that higher pressures equal higher temperatures, yes I can see a thicker oil leading to higher oil temps. Not to mention the engine is working harder to pump the thicker oil, generating more heat. And other things mentioned above. Makes sense to me.

It takes more power to move the oil .
Posted By: demarpaint

Re: Higher viscosity = higher operating temps? - 09/10/19 01:02 PM

Originally Posted by rooflessVW
Originally Posted by demarpaint
Originally Posted by gfh77665
Your 5w-30 ends up being a 5w-20 before you change it anyway...

Mine hasn't.

It's a ridiculous argument anyway. If a 30 shears down, then a 20 will too.


The 30 grade shearing down to a 20 is getting old fast. In a healthy engine with a good oil, running sane intervals there should be no problems with a 30 grade dropping to a 20 grade.
Posted By: 2015_PSD

Re: Higher viscosity = higher operating temps? - 09/10/19 01:55 PM

Originally Posted by ChrisD46
*Does the Rubicon OM list additional approved oil viscosities - or just the one ? In my Hyundai/Kia the OM lists 5W20 , 5W30 or 10W30 as being allowed - with the caveat that oil viscosity should be chosen based on the anticipated ambient temps during the upcoming OCI . I take this Hyundai/Kia statement to read : "While 5W20 is acceptable - 5W30 or 10W30 will provide more engine protection during the summer months" .
No; globally from 2019 onwards, they only specify 0W-20 for the 3.6L and 0/5W-30 for the 2.0L Turbo
Posted By: 2015_PSD

Re: Higher viscosity = higher operating temps? - 09/10/19 01:57 PM

Originally Posted by alarmguy
I have agreed for a long time on the bearing thing but here is why, just found this, "Too thick oil, wonderful oil pressure, yet parts inside the engine could actually be starved for oil due to lowered volume. Another downer, circulating oil accounts for nearly 50% of engine cooling, so reduced oil-flow reduces cooling causing lubricated parts to operate at higher temperatures. Higher parts temperatures, more wear."
I am not concerned with "oil starvation"; modern engines have positive displacement pumps and the oil pressure remained the same for both oils (about 31 PSI at highway speeds). At 210-225°F oil temperatures, I would have to believe the oil is "thin enough" to reach all of the critical places.
Posted By: 2015_PSD

Re: Higher viscosity = higher operating temps? - 09/10/19 01:59 PM

Originally Posted by zeng
Originally Posted by 2015_PSD
I saw a 10°F minimum temperature delta from 0W-20 to 0W-40 and wanted to see if my situation was unique or it was expected. There are always trade-offs and compromises between viscosities and one thing that stuck out for me was at what point is the increased temperature a detriment over the benefit of high viscosity oil.


Originally Posted by 2015_PSD
Yes; and I have since swapped back and forth from 0W-20 to 0W-40 and back to 0W-20 and have seen similar temperatures from each viscosity--though the 0W-40 will go a little higher (2-4°F). This engine seems to run at higher temperatures than what I am used to seeing, but from what I see on the Jeep forums, it is pretty normal (cannot say that I like it though). The 3.6L Pentastar was originally specified to run 5W-30 and was used in other countries until 2019 when 0W-20 was specified and at this point all countries specify 0W-20. With that said, I would have no issues running 5W-30 in it and I will likely continue with 0W-40 as I have a large stash of it from my AMG.

For a 0Wx0 full synthetic oil , I won't be bothered with operating temperature range of 80*C (180*F) and 105*C (220*F) in the context of temperature-driven 'accelerated' oil oxidation.
Instead a thicker oil in 0W40 'gains' higher MOFT over a thinner oil in 0W20 or 0W30 at no additional purchase cost , in fact lower cost in my market .
Zeng - agreed and since both oils are within a few degrees of each other, the MOFT provided by the 0W-40 has some benefits over the 0W-20 when working the engine.
Posted By: Jimmy_Russells

Re: Higher viscosity = higher operating temps? - 09/10/19 03:25 PM

Run nothing but 20 weight in mine and no issues. Spent many consecutive days in Moab heat, 20 hour drive each way, etc etc. The Pentastar just doesn't seem very hard on oil at all, usually do about 7-7.5k OCI. Absolutely tons of oil pressure too. I've never tried a 30 weight because it doesn't at all seem necessary based on my results with 20 weight.
Posted By: rideahorse

Re: Higher viscosity = higher operating temps? - 09/10/19 04:20 PM

Well let me tell you that just driving a car down the road is not working it at all. You are only using about 20% of it possible available hp. Now put that in a engine in Agriculture or the dirt working equipment that are running 100% of their hp and see how long your engine last. And I am talking about $80,000 engines vs your $2,000 engine. There is a reason you don't see thin oils in engines that have to work.
Posted By: PimTac

Re: Higher viscosity = higher operating temps? - 09/10/19 04:25 PM

I’m sure his engine is worth more than $2000 but your point is taken. It is a Apple’s to oranges comparison though.

Modern engines generally don’t work very hard in normal driving routines.
Posted By: loneryder

Re: Higher viscosity = higher operating temps? - 09/10/19 05:09 PM

[No; globally from 2019 onwards, they only specify 0W-20 for the 3.6L and 0/5W-30 for the 2.0L Turbo
[/quote]
Are they trying to tell us that they re-engineered the 3.6 to much tighter tolerances so the 5-30 they have spec'd for years is too thick now? I think not. It's for CAFE only. That's all they care about. Watch them go to 0-16 and 0-8 when it comes out. All they care about is getting the original owner out of warranty with acceptable failure numbers. It sounds to me like a lot of guys on here are going to use 0-16 and lower for "better flow and lower temps".
Posted By: rooflessVW

Re: Higher viscosity = higher operating temps? - 09/10/19 10:23 PM

Originally Posted by rideahorse
Well let me tell you that just driving a car down the road is not working it at all. You are only using about 20% of it possible available hp. Now put that in a engine in Agriculture or the dirt working equipment that are running 100% of their hp and see how long your engine last. And I am talking about $80,000 engines vs your $2,000 engine. There is a reason you don't see thin oils in engines that have to work.

The reason is cost and commonality. Keep a few drums of 15W-40 and it covers all the equipment.

If an HD engine was designed to use a synthetic 0W-20, well, it would work just fine.
Posted By: CR94

Re: Higher viscosity = higher operating temps? - 09/11/19 12:09 AM

Originally Posted by CT8
Originally Posted by CR94
So the 5W-30 part maintains a thick film, while the 5W-20 part reaches out into "tighter tolerance engine parts" where only it can fit?
What parts in an engine have a clearance so tight [ tolerance is the allowed variance of the clearance ] that only a 20 wt will reach?
None.
Posted By: Rav4H2019

Re: Higher viscosity = higher operating temps? - 09/11/19 02:46 AM

The preferred oil for new 2019 rav4 hybrid in USA is 0w16. Higher viscosities are allowed for high speed driving and extreme loads etc. The Australian rav4 hybrid allows upto 15w40 in warmer temps.
Posted By: Bryanccfshr

Re: Higher viscosity = higher operating temps? - 09/11/19 02:59 AM

No difference in performance between 0w20 and 0w40 in my Tacoma or 4 runner.
As always mileage is impacted by short trips, while longer trips where the oil warms up to operating temps yield the best mileage.

Increased oil temperatures with higher viscosities are normally attributed to viscous friction. The engine isn’t working harder enough to notice but the higher viscosity oil film resist shearing and allowing moving parts to touch. The cost of this is heat.
Fortunately many vehicles have oil to coolant coolers and the oil temp is relatively stable in the sump.
Posted By: Mad_Hatter

Re: Higher viscosity = higher operating temps? - 09/11/19 03:08 AM

Originally Posted by Bryanccfshr
No difference in performance between 0w20 and 0w40 in my Tacoma or 4 runner.
As always mileage is impacted by short trips, while longer trips where the oil warms up to operating temps yield the best mileage.

Increased oil temperatures with higher viscosities are normally attributed to viscous friction. The engine isn’t working harder enough to notice but the higher viscosity oil film resist shearing and allowing moving parts to touch. The cost of this is heat.
Fortunately many vehicles have oil to coolant coolers and the oil temp is relatively stable in the sump.


+1 i personally would take a hit to fuel economy in lieu of a thicker oil film. Now there are limits on this, it is possible to run too thick of a lube where internal parts are not getting adequate lubrication and the lubricants ability to cool is reduced.
Posted By: wemay

Re: Higher viscosity = higher operating temps? - 09/11/19 07:49 AM

Thicker oils absolutely contribute to higher operating temperatures just like they also offer better protection. But both are as minuscule as the mpg gains a lower viscosity oil contributes. All of these are facts that make chosing between one grade up or down a wash under normal daily driving conditions. Hence the difference of spec'd viscosity for different countries in the same geographical regions with no discernible difference in operating lifespans of the vehicles.
Posted By: yowps3

Re: Higher viscosity = higher operating temps? - 09/11/19 10:26 AM

Only reason for 20, 16, 8 wts is for sticker economy. In reality you'll get more lubricity and oil film in a 0w40 than 0w20.

Not to mention more resistance to fuel dilation, reduced shear rate and reduced chances of LSPI etc

Ever wonder why LSPI in unheard of in euro TGDI. Answer is xW40 oil!
Posted By: demarpaint

Re: Higher viscosity = higher operating temps? - 09/11/19 10:42 AM

I'd rather have better protection of my engine, giving up a small amount of fuel economy and running a few degrees hotter at operating temperature. The fuel savings I'm not capable of measuring, and the temperature difference is so slight that I haven't noticed it. I'm not suggesting using a 50 grade oil in an engine recommended for a 20 grade oil, but I see zero downside to running a 30 grade oil in a 20 grade oil application.
Posted By: alarmguy

Re: Higher viscosity = higher operating temps? - 09/11/19 01:49 PM

Originally Posted by 2015_PSD
Originally Posted by alarmguy
I have agreed for a long time on the bearing thing but here is why, just found this, "Too thick oil, wonderful oil pressure, yet parts inside the engine could actually be starved for oil due to lowered volume. Another downer, circulating oil accounts for nearly 50% of engine cooling, so reduced oil-flow reduces cooling causing lubricated parts to operate at higher temperatures. Higher parts temperatures, more wear."
I am not concerned with "oil starvation"; modern engines have positive displacement pumps and the oil pressure remained the same for both oils (about 31 PSI at highway speeds). At 210-225°F oil temperatures, I would have to believe the oil is "thin enough" to reach all of the critical places.


Oh I was just posting the article, you asked if higher viscosity could result higher oil temperatures. I posted the link to show why it can.

No way are you starving your engine for oil using a 30 weight. In fact I only use 5w30 in all my vehicles that call for 5/20 and 0/20 but also say 5/30 is ok.
Ill never use a 20, way more so in my hot climate.


Lets face it, 5/20 and 0/20 is ONLY for EPA meeting gas mileage and so slight a vehicle owner will NEVER see it but for manufacturers the tiny percent savings adds up.
Also, of course, if you live in an area where winter temps are below zero, it certainly cant hurt and would be my choice.


Posted By: Lowflyer

Re: Higher viscosity = higher operating temps? - 09/12/19 12:38 AM

Originally Posted by 2015_PSD
Has anyone seen an oil temperature increase by moving from say an xW-20 to an xW-40 (with everything remaining the same)?
Nope. But from 0W-40 to thicker sort of 5W-50 (on the "Nordschleife"). VCDS logs says on same weather: ~4-5°C hotter.

Change it to 5W-40 and all is fine.
Posted By: ZeeOSix

Re: Higher viscosity = higher operating temps? - 09/12/19 09:28 AM

Originally Posted by rideahorse
Well let me tell you that just driving a car down the road is not working it at all. You are only using about 20% of it possible available hp. Now put that in a engine in Agriculture or the dirt working equipment that are running 100% of their hp and see how long your engine last. And I am talking about $80,000 engines vs your $2,000 engine. There is a reason you don't see thin oils in engines that have to work.


Also, there's no CAFE requirements for agricultural engine use. Auto makers go as thin as possible to get every sliver of added gas mileage and still maintain good enough engine longevity. Many technical SAE type papers have shown use of thinner oil does increase engine wear over the long run. It might not be noticable to the guy behind the wheel during ownership, but it does happen.
Posted By: RDY4WAR

Re: Higher viscosity = higher operating temps? - 09/13/19 12:52 PM

With higher viscosity oil than the engine is clearanced / designed for, I'm more worried about bearing temperature than oil temperature.
Posted By: 2015_PSD

Re: Higher viscosity = higher operating temps? - 09/13/19 04:18 PM

Originally Posted by RDY4WAR
With higher viscosity oil than the engine is clearanced / designed for, I'm more worried about bearing temperature than oil temperature.
One would reflect the other, would it not--I cannot see how the oil would not heat up in response to the bearings increasing their temperature? Also, what engine would be clearanced/designed for a single viscosity? Not being sarcastic--just learning...
Posted By: Cujet

Re: Higher viscosity = higher operating temps? - 09/13/19 04:25 PM

It's good to remember that higher operating temperatures are a fact when higher viscosity is chosen, but that's only at higher RPM. At the low RPM's we typically see in today's engines, there really is little difference.

For track days, the use of 5/10/15W-50 viscosity oil is still common in many newer vehicles. Including Ford and GM toys. In some engines, the increase in operating temps due to track use reduces the viscosity of thinner oils into risk territory. Where the same cannot be said about the higher viscosity oils.
Posted By: RDY4WAR

Re: Higher viscosity = higher operating temps? - 09/13/19 04:33 PM

Originally Posted by 2015_PSD
Originally Posted by RDY4WAR
With higher viscosity oil than the engine is clearanced / designed for, I'm more worried about bearing temperature than oil temperature.
One would reflect the other, would it not--I cannot see how the oil would not heat up in response to the bearings increasing their temperature? Also, what engine would be clearanced/designed for a single viscosity? Not being sarcastic--just learning...


With higher viscosity, the temperature delta through the bearings will be higher. With sufficient surface area of the pan and coolant temperature through the block, the oil temp may not rise but 5*F but the bearings can be 20-30*F hotter.

There's an ideal flow vs viscosity through the rod and main bearings. Too much flow from too little viscosity risks cavitation. Too little flow from too much viscosity reduces cooling and increases hydrodynamic friction. More friction + less flow = more heat.

The ideal oil viscosity is dependent on the bearing clearances and operating oil temperature. Some hydraulic lifters are picky about viscosity as well (GM LS based engines, for example). Here's a chart of comparing bearing clearance to temperature for ideal oil grade / viscosity. The majority of modern OEM engines have between .0010-.0018" rod and main bearing clearance.



Attached picture main and rob clearances to oil viscosity.jpg
Posted By: Mad_Hatter

Re: Higher viscosity = higher operating temps? - 09/14/19 12:33 AM

Originally Posted by RDY4WAR
Originally Posted by 2015_PSD
Originally Posted by RDY4WAR
With higher viscosity oil than the engine is clearanced / designed for, I'm more worried about bearing temperature than oil temperature.
One would reflect the other, would it not--I cannot see how the oil would not heat up in response to the bearings increasing their temperature? Also, what engine would be clearanced/designed for a single viscosity? Not being sarcastic--just learning...


With higher viscosity, the temperature delta through the bearings will be higher. With sufficient surface area of the pan and coolant temperature through the block, the oil temp may not rise but 5*F but the bearings can be 20-30*F hotter.

There's an ideal flow vs viscosity through the rod and main bearings. Too much flow from too little viscosity risks cavitation. Too little flow from too much viscosity reduces cooling and increases hydrodynamic friction. More friction + less flow = more heat.

The ideal oil viscosity is dependent on the bearing clearances and operating oil temperature. Some hydraulic lifters are picky about viscosity as well (GM LS based engines, for example). Here's a chart of comparing bearing clearance to temperature for ideal oil grade / viscosity. The majority of modern OEM engines have between .0010-.0018" rod and main bearing clearance.


Nice find on the chart.👍.. I've read that 10cSt was the "ideal" viscosity for bearing clearances? "Much higher than this and drag results, much lower than this and boundary lubrication occurs" in link below 👇. (what I said in my previous post).. now the question for me, at what point does boundary lubrication become an issue? 8cst?..7 or 6?

KEW Engineering
Posted By: CR94

Re: Higher viscosity = higher operating temps? - 09/14/19 02:39 AM

Interesting chart, RDY4WAR. Assuming the intermediate temperature range, it would've had put 0W-20 or 0W-10 in my 1981 Mazda, for which the service manual specified 0.0009" to 0.0017 clearance for mains.
Posted By: ZeeOSix

Re: Higher viscosity = higher operating temps? - 09/14/19 03:50 AM

Originally Posted by CR94
Interesting chart, RDY4WAR. Assuming the intermediate temperature range, it would've had put 0W-20 or 0W-10 in my 1981 Mazda, for which the service manual specified 0.0009" to 0.0017 clearance for mains.


What did Mazda specify for that engine?
Posted By: Mad_Hatter

Re: Higher viscosity = higher operating temps? - 09/14/19 05:20 AM

Originally Posted by CR94
Interesting chart, RDY4WAR. Assuming the intermediate temperature range, it would've had put 0W-20 or 0W-10 in my 1981 Mazda, for which the service manual specified 0.0009" to 0.0017 clearance for mains.

I think those are the optimal viscosities for those clearances. That doesn't mean other viscosities wouldn't be suitable, they just might not be "optimal".

The optimal viscosity is one that provides a) a MOFT that prevents catastrophic wear and b) one not so thick that it creates excessive heat via viscous drag (the lube itself is so thick that it creates friction/heat) and flow reduction. The heat wears on bearings and robs the engine of power and in turn fuel economy.

Many lubes (like an Xw30) could satisfy this requirement so long as the HTHS isn't too high. This is where base oil viscosity and VM type and quantity come in. Too high a 150c HTHS can actually increase wear rates in tight clearances. A case where more is not necessarily a good thing.
Posted By: CR94

Re: Higher viscosity = higher operating temps? - 09/14/19 05:52 AM

Originally Posted by ZeeOSix
Originally Posted by CR94
... Assuming the intermediate temperature range, it would've had put 0W-20 or 0W-10 in my 1981 Mazda, for which the service manual specified 0.0009" to 0.0017 clearance for mains.

What did Mazda specify for that engine?
API SE. The manual shows an old-fashioned chart with many viscosity grade options.
5W-20 between -35 and -20°C
5W-30 between -35 and 0°C
10W-30 between -25 and 30°C
10W-40 between -25 and 55°C
10W-50 between -25 and 55°C
20W-20 between -10 and 20°C
20W-40 between -10 and 55°C
20W-50 between -10 and 55°C
SAE 30 between 0 and 40°C
SAE 40 between 30 and 55°C

I'm not claiming that's all logical. Obviously they didn't have much confidence in shear stability of 5W-x0s of 1980. I mostly used 10W-40, with occasional bouts of 10W-30 in cool weather. Never any issues with wear of oily metal parts in 606k miles.
Posted By: OilUzer

Re: Higher viscosity = higher operating temps? - 09/14/19 07:21 AM

In the old days they were wiser and used thicker oil. don't worry, the internet people will learn from history and will join the thickies club! LOL

Originally Posted by CR94
API SE. The manual shows an old-fashioned chart with many viscosity grade options.
5W-20 between -35 and -20°C
5W-30 between -35 and 0°C
10W-30 between -25 and 30°C
10W-40 between -25 and 55°C
10W-50 between -25 and 55°C
20W-20 between -10 and 20°C
20W-40 between -10 and 55°C
20W-50 between -10 and 55°C
SAE 30 between 0 and 40°C
SAE 40 between 30 and 55°C

I'm not claiming that's all logical. Obviously they didn't have much confidence in shear stability of 5W-x0s of 1980. I mostly used 10W-40, with occasional bouts of 10W-30 in cool weather. Never any issues with wear of oily metal parts in 606k miles.
Posted By: ka9mnx

Re: Higher viscosity = higher operating temps? - 09/14/19 10:27 PM

Originally Posted by CR94
Interesting chart, RDY4WAR. Assuming the intermediate temperature range, it would've had put 0W-20 or 0W-10 in my 1981 Mazda, for which the service manual specified 0.0009" to 0.0017 clearance for mains.

Yes, interesting chart. That would work for your Mazda bearings but remember 40% of engine friction is in the liner, piston and ring area. It is also the most prone area of oil breakdown (viscosity loss). So it would probably be a bad idea for the ring/liner area.
Posted By: Cujet

Re: Higher viscosity = higher operating temps? - 09/15/19 02:35 AM

That chart makes little sense with regard to rod bearings. The clearances quoted have little resemblance to any previous or common era conventional engines. The rule is about or around 0.0007 inches of rod bearing clearance, per inch of journal diameter. With wiggle room of 0.0005 inches for rigidity reasons. It's been that way for 50+ years.

Generally only race engines with high viscosity oils do otherwise.

Factors such as crank and block rigidity are major reasons older engines would last longer with larger clearances.

RPM drives the rod bearing size and oil requirements. Many direct injection engines don't rev as high as engines from the recent past. Allowing smaller bearing diameters and the resulting tighter clearances.
Posted By: RDY4WAR

Re: Higher viscosity = higher operating temps? - 09/15/19 03:20 AM

Originally Posted by ka9mnx
Originally Posted by CR94
Interesting chart, RDY4WAR. Assuming the intermediate temperature range, it would've had put 0W-20 or 0W-10 in my 1981 Mazda, for which the service manual specified 0.0009" to 0.0017 clearance for mains.

Yes, interesting chart. That would work for your Mazda bearings but remember 40% of engine friction is in the liner, piston and ring area. It is also the most prone area of oil breakdown (viscosity loss). So it would probably be a bad idea for the ring/liner area.


The rings also operate in boundary and mixed lubrication, where the additive package has a far greater impact on wear and friction than the base oil.
Posted By: ZeeOSix

Re: Higher viscosity = higher operating temps? - 09/15/19 05:43 AM

Originally Posted by Cujet
That chart makes little sense with regard to rod bearings. The clearances quoted have little resemblance to any previous or common era conventional engines.


I believe the Ford Coyote 5.0L V8 has minimum rod clearance of 0.001", might even be a hair less. I'll look in the factory sevice manual and snip-it and post later.

Posted By: Mad_Hatter

Re: Higher viscosity = higher operating temps? - 09/15/19 07:31 AM

Originally Posted by RDY4WAR

The rings also operate in boundary and mixed lubrication, where the additive package has a far greater impact on wear and friction than the base oil.

Good point..+1.. this is where your EP addys come into play due to the temps/pressures.
Posted By: ka9mnx

Re: Higher viscosity = higher operating temps? - 09/15/19 12:27 PM

Originally Posted by Mad_Hatter
Originally Posted by RDY4WAR

The rings also operate in boundary and mixed lubrication, where the additive package has a far greater impact on wear and friction than the base oil.

Good point..+1.. this is where your EP addys come into play due to the temps/pressures.

The oil DOES operate at boundary lubrication with the designed oil. Running a lower grade oil puts the rings at TDC (thinned because of heat) in jeopardy

Analysis of Parasitic Losses in Heavy Duty Diesel Engines
by Christopher Joseph James
B.S. Mechanical Engineering
Northeastern University, 2010.

In this analysis a 50% reduction in lubricant viscosity predicted approximately 25% decrease in power cylinder friction.
It should be noted that a 50% reduction in lubricant viscosity would dramatically increase wear
rates in the power cylinder and would not be technically feasible without aggressive wear
mitigation strategies.

(Thanks Shannow)
Posted By: MetalSlug

Re: Higher viscosity = higher operating temps? - 09/15/19 01:12 PM

Made me want go back 0w20 instead of 5w30 on my i4 Honda Accord 2011
Posted By: RDY4WAR

Re: Higher viscosity = higher operating temps? - 09/15/19 03:44 PM

Originally Posted by ka9mnx
Originally Posted by Mad_Hatter
Originally Posted by RDY4WAR

The rings also operate in boundary and mixed lubrication, where the additive package has a far greater impact on wear and friction than the base oil.

Good point..+1.. this is where your EP addys come into play due to the temps/pressures.

The oil DOES operate at boundary lubrication with the designed oil. Running a lower grade oil puts the rings at TDC (thinned because of heat) in jeopardy

Analysis of Parasitic Losses in Heavy Duty Diesel Engines
by Christopher Joseph James
B.S. Mechanical Engineering
Northeastern University, 2010.

In this analysis a 50% reduction in lubricant viscosity predicted approximately 25% decrease in power cylinder friction.
It should be noted that a 50% reduction in lubricant viscosity would dramatically increase wear
rates in the power cylinder and would not be technically feasible without aggressive wear
mitigation strategies.

(Thanks Shannow)


This is assuming you're comparing base oils of similar pressure-viscosity coefficient and same additive package. Even when not, the experience with the high rpm alcohol engines I mentioned earlier showed little difference in wear with huge jumps in viscosity SAE 50 to 0w-3. The only area where wear was more apparent with the thinner oil was in the bearings. Reducing the ZDDP and MoDTC content by 20% had a much larger effect on wear of the rings and cylinders than the base oil viscosity. This was measured by tearing the engine down after 100 or so 1/4 mile passes, with oil changes every 25 passes, and accurately mic'ing everything. As a side note, Rotella T4 15w-40 (older CJ-4 formula) was run through these engines as well and 4 of the 16 cam lobes failed inspection after 100 passes due to loss of lobe lift. These engines are also running billet solid roller cams with over .900" valve lift and near 1,000 lbs of spring pressure which is well more than that oil was ever designed to withstand.

Another observation is that the wear rates were greater at lower oil temperature than higher, despite lower viscosity at higher temperature, which also indicates the additive package being a greater variable than viscosity as your anti-wear and friction modifier additives require heat to activate.

Think of it like sending an army into battle. You can send the most elite, well-trained men (base oil) into the fight, but if you don't give them weapons to fight with (additives), they're just cannon fodder.
Posted By: ka9mnx

Re: Higher viscosity = higher operating temps? - 09/15/19 04:22 PM

Duly noted but you are comparing a 1/4 mile engine to a grocery getter. Apples to oranges.
Posted By: Lowflyer

Re: Higher viscosity = higher operating temps? - 09/15/19 07:10 PM

Originally Posted by RDY4WAR
Reducing the ZDDP and MoDTC content by 20% had a much larger effect on wear of the rings and cylinders than the base oil viscosity.
Sorry. No. What gives you that idea?
Posted By: RDY4WAR

Re: Higher viscosity = higher operating temps? - 09/15/19 07:42 PM

Originally Posted by Lowflyer
Originally Posted by RDY4WAR
Reducing the ZDDP and MoDTC content by 20% had a much larger effect on wear of the rings and cylinders than the base oil viscosity.
Sorry. No. What gives you that idea?


The micrometers don't lie. It didn't matter what viscosity of oil was in the engine. The rings, pistons, and cylinders just didn't care. Same wear observed regardless of viscosity. Minor changes in the additive package had a much larger effect on cylinder wear than major jumps in viscosity. The only part of the engine that cared about the oil's viscosity were the bearings. That's a solid roller engine though. An engine with hydraulic lifters can be picky about viscosity depending on bleed down rates, and usually the issue is with too high viscosity rather than too low. Morel hydraulic lifters are a prime example. Anything above around 15 cSt and they tend to chatter.
Posted By: Lowflyer

Re: Higher viscosity = higher operating temps? - 09/15/19 08:24 PM

oil-club.de have a UOA of forgery, I mean, M1 5W-50. Looks like a mix of W60 und 75W-90 eek With a additives in the ballpark of 100 ZDDP (something like that). Yes, rofl.

Ok the driving profile was (fortunately) very unproblematic. And the wear values of UOA was not a big Wow... BUT, but it was also not disastrous (!) It was, I tell, medium of averages (UOAs).

Therefore ( who would have thought it?...): It is still and continue, the oil, that lubricate.
Base oil -> base, bedrock.
Addons -> adds. Useful, but not the bedrock.
Posted By: ZeeOSix

Re: Higher viscosity = higher operating temps? - 09/19/19 12:47 AM

Originally Posted by ZeeOSix
Originally Posted by Cujet
That chart makes little sense with regard to rod bearings. The clearances quoted have little resemblance to any previous or common era conventional engines.

I believe the Ford Coyote 5.0L V8 has minimum rod clearance of 0.001". I'll look in the factory sevice manual and snip-it and post later.


So I got around to looking up the main and rod clearances on the Ford Coyote 5.0L V8. As you can see they can be tight, around 0.001" minimum clearance. Even the piston to cylinder clearance can be pretty tight.

Even though the oil spec is 5W-20 for street use, Ford will recommend running 5W-50 for track use. So as usual, this shows that journal bearings (or other parts) clearance doesn't have much to do with what oil viscosity is specified for an engine.

[Linked Image]

Posted By: Cujet

Re: Higher viscosity = higher operating temps? - 09/19/19 02:15 AM

Originally Posted by ZeeOSix


So I got around to looking up the main and rod clearances on the Ford Coyote 5.0L V8. As you can see they can be tight, around 0.001" minimum clearance. Even the piston to cylinder clearance can be pretty tight.

Even though the oil spec is 5W-20 for street use, Ford will recommend running 5W-50 for track use. So as usual, this shows that journal bearings (or other parts) clearance doesn't have much to do with what oil viscosity is specified for an engine.





Yup, no different than engines from decades ago. The standard remains 0.0007 inches per inch of journal diameter, with 2 inch journals having as much as a 0.0005 inch leeway on the tight side, if desired. No magic there. As a general rule, trending towards the tight specification simply required excellent component structural stability at the expected loads, nothing more than that. While testing for Ford, we assembled engines to those specifications, 35+ years ago.

The performance engine builders that required "loose" clearances did so for reliability on structurally unsound equipment. Going "loose" was no faster, but it certainly was more reliable in some race situations.
Posted By: demarpaint

Re: Higher viscosity = higher operating temps? - 09/19/19 02:34 AM

Originally Posted by ZeeOSix
Originally Posted by ZeeOSix
Originally Posted by Cujet
That chart makes little sense with regard to rod bearings. The clearances quoted have little resemblance to any previous or common era conventional engines.

I believe the Ford Coyote 5.0L V8 has minimum rod clearance of 0.001". I'll look in the factory sevice manual and snip-it and post later.


So I got around to looking up the main and rod clearances on the Ford Coyote 5.0L V8. As you can see they can be tight, around 0.001" minimum clearance. Even the piston to cylinder clearance can be pretty tight.

Even though the oil spec is 5W-20 for street use, Ford will recommend running 5W-50 for track use. So as usual, this shows that journal bearings (or other parts) clearance doesn't have much to do with what oil viscosity is specified for an engine.

[Linked Image]


So much for the engines are being built so tight they "must" have a 20 grade oil in order to operate properly and not self destruct, as some allude to here.
Posted By: RDY4WAR

Re: Higher viscosity = higher operating temps? - 09/19/19 02:45 AM

Originally Posted by ZeeOSix
Originally Posted by ZeeOSix
Originally Posted by Cujet
That chart makes little sense with regard to rod bearings. The clearances quoted have little resemblance to any previous or common era conventional engines.

I believe the Ford Coyote 5.0L V8 has minimum rod clearance of 0.001". I'll look in the factory sevice manual and snip-it and post later.


So I got around to looking up the main and rod clearances on the Ford Coyote 5.0L V8. As you can see they can be tight, around 0.001" minimum clearance. Even the piston to cylinder clearance can be pretty tight.

Even though the oil spec is 5W-20 for street use, Ford will recommend running 5W-50 for track use. So as usual, this shows that journal bearings (or other parts) clearance doesn't have much to do with what oil viscosity is specified for an engine.

[Linked Image]



They are also assuming the street will see 200-220*F oil temps and the track will see >260*F oil temps. If you were to plot the viscosity, the KV150 of the 15w-50 would be pretty close to the KV100 of the 5w-20. Temperature is the other part of that equation that must be considered.

NHRA Pro Stock engines have rod and main bearing clearances around .0028-.0032" and use 0w-2/3 oil because their oil temp is 100-130*F.
Posted By: aquariuscsm

Re: Higher viscosity = higher operating temps? - 09/19/19 02:54 AM

Originally Posted by MetalSlug
Made me want go back 0w20 instead of 5w30 on my i4 Honda Accord 2011


I'm going back to 10W30 in my Accord.
Posted By: ChrisD46

Re: Higher viscosity = higher operating temps? - 09/19/19 04:59 AM

*I would also like to think - if say Hyundai/ Kia as example list owners manual approved oils as 5W20 , 5W30 and 10W30 (depending on ambient temps) then there is a bit of leeway in acceptable ouils based on key engine tolerances (albeit not as much as for the Mustang Coyote 5.0L).
Originally Posted by ZeeOSix
Originally Posted by ZeeOSix
Originally Posted by Cujet
That chart makes little sense with regard to rod bearings. The clearances quoted have little resemblance to any previous or common era conventional engines.

I believe the Ford Coyote 5.0L V8 has minimum rod clearance of 0.001". I'll look in the factory sevice manual and snip-it and post later.


So I got around to looking up the main and rod clearances on the Ford Coyote 5.0L V8. As you can see they can be tight, around 0.001" minimum clearance. Even the piston to cylinder clearance can be pretty tight.

Even though the oil spec is 5W-20 for street use, Ford will recommend running 5W-50 for track use. So as usual, this shows that journal bearings (or other parts) clearance doesn't have much to do with what oil viscosity is specified for an engine.

[Linked Image]

Posted By: Mad_Hatter

Re: Higher viscosity = higher operating temps? - 09/19/19 05:24 AM

Originally Posted by ChrisD46
*I would also like to think - if say Hyundai/ Kia as example list owners manual approved oils as 5W20 , 5W30 and 10W30 (depending on ambient temps) then there is a bit of leeway in acceptable ouils based on key engine tolerances (albeit not as much as for the Mustang Coyote 5.0L).

That was the gist of a previous post of mine. There's no such thing as a perfect oil. It just doesn't exist. Perform in one area, say low oil friction is gonna come at the expense of viscosity (hths/MOFT).

The Kia engine builders know what grade(s) are going to provide that MOFT (5/20 in my case) to avoid catastrophic metal to metal contact and which oil is going to be too thick that flow (starvation) and friction (oil drag) becomes a potential issue. And I'm glad they're transparent in this and allowing me the owner some flexibility in lube choices without worrying that I'm gonna void a warranty. ...I said that Honda knows full well there are other lubes besides a 0w20 that will work just fine in their engine. Question is, why are they not transparent in this?...I mean seriously, what happens when that 0w20 thickens up to a Xw30..is that Honda engine gonna spontaneously grenade???😂
Posted By: ZeeOSix

Re: Higher viscosity = higher operating temps? - 09/19/19 06:21 AM

Originally Posted by Mad_Hatter
The Kia engine builders know what grade(s) are going to provide that MOFT (5/20 in my case) to avoid catastrophic metal to metal contact and which oil is going to be too thick that flow (starvation) and friction (oil drag) becomes a potential issue.


I don't think there is any "oil starvation" unless a thick oil is used in temperatures much colder than what the oil is speced for. When car makers spec 0W-20 or 5W-20 then by default you get good cold weather cold start oil flow.

Using 10W-30 instead of 0W-20 in say above 50F weather isn't going to result in any oil starvation.

Originally Posted by Mad_Hatter
And I'm glad they're transparent in this and allowing me the owner some flexibility in lube choices without worrying that I'm gonna void a warranty. ...I said that Honda knows full well there are other lubes besides a 0w20 that will work just fine in their engine. Question is, why are they not transparent in this?...I mean seriously, what happens when that 0w20 thickens up to a Xw30..is that Honda engine gonna spontaneously grenade???😂


Honda is playing the CAFE game pretty hard, therefore they won't even mention any oil viscosity options in their manuals. They might in countries outside the USA like other car makers do.
Posted By: Mad_Hatter

Re: Higher viscosity = higher operating temps? - 09/19/19 07:44 AM

Originally Posted by ZeeOSix
Originally Posted by Mad_Hatter
The Kia engine builders know what grade(s) are going to provide that MOFT (5/20 in my case) to avoid catastrophic metal to metal contact and which oil is going to be too thick that flow (starvation) and friction (oil drag) becomes a potential issue.


I don't think there is any "oil starvation" unless a thick oil is used in temperatures much colder than what the oil is speced for. When car makers spec 0W-20 or 5W-20 then by default you get good cold weather cold start oil flow.

Using 10W-30 instead of 0W-20 in say above 50F weather isn't going to result in any oil starvation.

Originally Posted by Mad_Hatter
And I'm glad they're transparent in this and allowing me the owner some flexibility in lube choices without worrying that I'm gonna void a warranty. ...I said that Honda knows full well there are other lubes besides a 0w20 that will work just fine in their engine. Question is, why are they not transparent in this?...I mean seriously, what happens when that 0w20 thickens up to a Xw30..is that Honda engine gonna spontaneously grenade???😂


Honda is playing the CAFE game pretty hard, therefore they won't even mention any oil viscosity options in their manuals. They might in countries outside the USA like other car makers do.

In my original, in context, post I said a [gross] deviation of the recommended viscosities can cause oil starvation. Going from a 5w20 to a 10w30 generally wouldn't be considered a gross deviation...but going from a 5w20 to say a 15w40 might be. Just depends on factors like the engines pumping ability and tolerances. In older engines, thicker oil might be more desirable due to wider clearances in places like rings to piston. But...you go too thick and things like turbos and bearings can be starved of oil, or more accurately lack of lubrication. In these areas reduced flow and increased oil friction due to viscosity increase, can have potentially catastrophic effects.

The 2nd half i agree wholeheartedly...
Posted By: Lowflyer

Re: Higher viscosity = higher operating temps? - 09/19/19 09:19 AM

Originally Posted by Mad_Hatter
[quote=ChrisD46]The Kia engine builders know what grade(s) are going to provide that MOFT (5/20 in my case) to avoid catastrophic metal to metal contact and which oil is going to be too thick that flow (starvation) and friction (oil drag) becomes a potential issue.
Of course. But this must not be a 5W-20.

WWOs (Wee-Wee Oils) are a result of fuel consumption hysteric, as result of climatic hysteric. You self, will never find those 2 things between 5W-20 and for example to M1 5W-30 (504/507):

1. for you measurable less fuel consumption (equal)
2. one molecule more wear in your UOAs (rather more)

In Kia engines not and in Subaru engines also not.

Without doubt, Kia engine builders know what grades are best. The problem is, they determine it not alone.
Posted By: dlundblad

Re: Higher viscosity = higher operating temps? - 09/19/19 10:18 AM

I can’t see oil temps affecting coolant temps in any major way as the cooling system would just compensate for the higher temp within the engine. This is assuming the cooling system is 100% operational.

I believe oil temps would be higher with thicker oil, but I’m not sure that’s a bad thing within reason.
Posted By: aquariuscsm

Re: Higher viscosity = higher operating temps? - 09/19/19 11:43 AM

Originally Posted by ZeeOSix
Honda is playing the CAFE game pretty hard, therefore they won't even mention any oil viscosity options in their manuals. They might in countries outside the USA like other car makers do.


This.

I saw an actual 2012 Accord owner's manual from another country and it says to use W30 oil.
Posted By: 2015_PSD

Re: Higher viscosity = higher operating temps? - 09/19/19 12:36 PM

Originally Posted by demarpaint
Originally Posted by ZeeOSix
Originally Posted by ZeeOSix
Originally Posted by Cujet
That chart makes little sense with regard to rod bearings. The clearances quoted have little resemblance to any previous or common era conventional engines.

I believe the Ford Coyote 5.0L V8 has minimum rod clearance of 0.001". I'll look in the factory sevice manual and snip-it and post later.


So I got around to looking up the main and rod clearances on the Ford Coyote 5.0L V8. As you can see they can be tight, around 0.001" minimum clearance. Even the piston to cylinder clearance can be pretty tight.

Even though the oil spec is 5W-20 for street use, Ford will recommend running 5W-50 for track use. So as usual, this shows that journal bearings (or other parts) clearance doesn't have much to do with what oil viscosity is specified for an engine.

[Linked Image]


So much for the engines are being built so tight they "must" have a 20 grade oil in order to operate properly and not self destruct, as some allude to here.
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