Higher speeds, heavier oils?

[Shannow]

Originally Posted By: HTSS_TR
It may not hours, but in some stretch of Autobahn you can run WOT at redline for considerable distance, this can raise oil temp 20-30C or higher than what we can see in US highway.

My point is oil temperature of an engine that run at 5-6k RPM is much higher than 2-3k RPM. So, it depends on how a driver is using his vehicle(s) he/she may need to select oil accordingly.


Demonstrated amply well in my Caprice (L67 supercharged 3.8).

in 15 minutes at 100km/h in "D", a type K thermocouple down the dipstick reads 100-105...extend that by another 15 minutes and it's still 105C.

Hold it in "2", 4,000RPM for exactly the same road speed/load, and in that 15 mins from cold, it will read 135C.

No idea what the local viscosity is in the big ends (they will be hotter for sure), and quite sure that 10 mins every now and then for this type of experiment isn't consuming huge amounts of engine life...

 

[Yup]

My issue is light weight and high RPMs seems to vaporize. Thing drinks quarts per thousand pulling 4500 RPMs high speed on highway. Throw a 5w30 or 5w40 and almost no consumption.

 

[IndyIan]

Originally Posted By: Shannow

Where load DOES come in is the minimum oil film thickness, but a lot of OEMs are accepting that they are going to operate in boundary and mixed regimes to improve economy (or carbon emissions if that's the bent of your local legislators).

Really? That sounds a bit risky, especially with a manual trans, but there are fewer of those all the time. Sounds like a good reason to go up a grade anyways, if you are working the engine a bit harder than typical use.

 

[BrocLuno]

Exactly, Drag cars that run 90% of their time (under load) above 5,000 RPM all run thicker oils (pre-heated if need be). Only racers with extremely deep pockets (sponsors) will chance light oils for a few HP gain. The carnage is just not worth it ...

 

[FCD]

I have been on the autobahn quite a few times with my Ford Capri, driving at 100 Mph the engine got significantly hotter than driving at 60 or 70 like i do here, at 110 my car is almost at WOT and turning about 5000 rpm ( maximum safe rpm is 6500 ) i overheated it once despite it being winter and it being absolutely freezing outside, opening the hood/bonnet felt like stepping into a sauna! once it cooled off though it ran really smooth and felt more responsive.

 

[Jeff_in_VABch]

I may have missed it, but do you know what your oil pressure is at maximum speed?

Generally speaking, and depending upon a lot of factors, you would want a lower viscosity oil at high engine RPM.

A high viscosity oil could activate the oil pressure bypass at high RPM, generate heat and incur unneeded pumping losses. Of course an old, hot running engine with large bearing clearances might need a higher viscosity oil to maintain oil pressure.

On the other end of the spectrum, a slow running engine at low speed and high temperature certainly needs a higher viscosity oil to maintain oil pressure and provide protection.

 

[Shannow]

re activating the oil pump relief...there's 50 Watts (one headlamp) difference in pump generated heat between 60 and 80 psi.

Running the oil pump in relief isn't significant when viscous drag is whole KWs.

Oil pressure doesn't lubricate.

 

[Shannow]

Originally Posted By: IndyIan
Originally Posted By: Shannow

Where load DOES come in is the minimum oil film thickness, but a lot of OEMs are accepting that they are going to operate in boundary and mixed regimes to improve economy (or carbon emissions if that's the bent of your local legislators).

Really? That sounds a bit risky, especially with a manual trans, but there are fewer of those all the time. Sounds like a good reason to go up a grade anyways, if you are working the engine a bit harder than typical use.


Here's some stuff I've linked to in the past.

https://bobistheoilguy.com/forums/ubbthreads.php/topics/3073277/GF-5,_economy,_Striebeck_curve

They are using "new" engines in the engine test sequences as they are purposely being designed into mixed regime these days.

https://bobistheoilguy.com/forums/ubbthreads.php/topics/3390995/Why_designers_allow_mixed_lubr

showing the frictional benefits.

Note that reduced "friction" doesn't automatically always mean reduced wear.

 

[CATERHAM]

Originally Posted By: Jeff_in_VABch
I may have missed it, but do you know what your oil pressure is at maximum speed?

Generally speaking, and depending upon a lot of factors, you would want a lower viscosity oil at high engine RPM.

A high viscosity oil could activate the oil pressure bypass at high RPM, generate heat and incur unneeded pumping losses. Of course an old, hot running engine with large bearing clearances might need a higher viscosity oil to maintain oil pressure.

On the other end of the spectrum, a slow running engine at low speed and high temperature certainly needs a higher viscosity oil to maintain oil pressure and provide protection.

I agree, an OP gauge is a marvelous time tested tool that will tell one if the oil is too thick or too thin in an operating engine.
But to clarify for some, the oil pressure you're referring is actually the reading on an OP gauge which indicates the back-pressure in the system. Therefore the lower the OP reading, the lower the viscosity of the oil. Maintaining a known safe minimum OP is therefore the same as maintaining a known safe minimum operational viscosity.

As you correctly stated, an OP gauge will also tell you when the oil pump by-pass is activated. And if it is at maximum rev's with the oil at operating temp's, then the oil is too thick which may adversely affect engine lubrication and cooling.

 

[CT8]

Originally Posted By: TheOnlySarge
Come on down to Texas and open it up. Get out to West Texas/Central Texas and your on the Texas Autobahn

Dallas to San Antonio is like London-Glasgow and back!
I lived in the UK for years....Europe embraced the extended drain long before we did and from living there and "talking cars" I believe they still embrace the thicker for extended OCI runs mentality and it has nothing to do with bearing clearance, Driving habits etc. etc.
Of course you and I know that todays oils do not shear anything like they did 15-20 years ago.
Most people can't tell the difference between a clearance and a tolerance. Yet they understand oil viscosity.

 

[aquariuscsm]

Originally Posted By: AEHaas
I removed the heavier, OEM spec'ed differential oil in my Ford Expedition, then replaced it with a lightweight gear oil. I felt comfortable doing this in FLAT Florida and I never tow anything. This was some years ago. I ran a specific course over again in otherwise the same conditions and measured the temperature with both lubricants. The lighter grade ran cooler though I do not remember the temperature difference. I took the temperature off the case.

aehaas


I agree with you on this. I tried a heavier oil in my car's rear diff (75W140) and it made it drag really bad and made it noisy.

 

[Jeff_in_VABch]

Originally Posted By: Shannow
re activating the oil pump relief...there's 50 Watts (one headlamp) difference in pump generated heat between 60 and 80 psi.

Running the oil pump in relief isn't significant when viscous drag is whole KWs.

Oil pressure doesn't lubricate.


8 GPM X 60 PSI X 0.0007 = 0.336 HP or 251 watts drive energy
8 GPM X 80 PSI X 0.0007 = 0.448 HP or 334 watts drive energy

However, most oil pump curves are inverse, as pump pressure goes up, flow goes down. So at higher pressure, flow would be reduced, and drive energy would be lessened. So on drive energy, you are pretty close.

Im not sure which viscous drag you are talking about, but since its hard to eliminate, it dosent matter. The windage and associated drag is a big deal, but using a lighter oil and increasing windage would reduce power but increase cooling due to increased flow.

You are also right that oil pressure doesn't lubricate, but a lack of oil pressure destroys.

Anyway, I get your point, rambling over.

 

[David_Corbett]

Originally Posted By: Jeff_in_VABch
I may have missed it, but do you know what your oil pressure is at maximum speed?


Unfortunately, no. It's a modern passenger car, so all I get is a heavily dampened coolant temperature gauge. I have no idea what the oil pressure, oil temperature, or transmission temperature is on my car.

It looks like there are a lot of differing opinions on this, but that unless I'm spending time north of 100 (unlikely) I'm not really dealing with the high temperatures that would necessitate a thicker oil.

I am concerned about the reports of valvetrain wear on Subaru and Toyota engines following a shift to 0W-20 oil, but Honda has been running XW20 oil for fifteen years now and certainly would have designed my engine to take full advantage of it. If I did go up, it'd be to a light thirty such as M1 AFE 0W30 or something to that effect.

In the mean time, I've got a VOA in on the Canadian formulation of Genuine Honda Full Synthetic 0W-20, to see if it's any good. Here's hoping they start selling Mobil1 EP 0W-20 up here as well - we only get the AFE model.

 

[buster]

Also to be considered - NOACK volatility. Your run of the mill 20 grade (II/II+ blend) will have a higher Noack figure (12-15%). Oil consumption can be an issue at high speeds with some 20 grades. If you drive at high speeds, I'd go up to a 30 grade, or use a good PAO based 0w20 like Mobil 1 EP. NOACK volatility is 10% for that oil which is very good.

 

[David_Corbett]

I'd love to use Mobil1 EP 0W-20. Unfortunately, I don't think they sell it up here in Canada yet. (While a lot of Canadians might be able to cross the border to do some shopping, such an option is not really feasible for Albertans. From Alberta's largest city, it's five hours each way to the nearest American towns of decent size, being Kalispell and Great Falls, MT.

 

[CATERHAM]

Originally Posted By: buster
Also to be considered - NOACK volatility. Your run of the mill 20 grade (II/II+ blend) will have a higher Noack figure (12-15%). Oil consumption can be an issue at high speeds with some 20 grades. If you drive at high speeds, I'd go up to a 30 grade, or use a good PAO based 0w20 like Mobil 1 EP. NOACK volatility is 10% for that oil which is very good.

A 5W-20 dino is not spec'd for this car but rather a 0W-20 and most premium 0W-20s have a Noack in the 10-13% range anyway.
That said, 85 mph is not "high speed" nor has the OP said he has an oil consumption issue.
Furthermore, all engines consume some oil and I've never seen any evidence that it's due to evaporation even at the 15% level.

 

[kschachn]

Originally Posted By: David_Corbett
I am concerned about the reports of valvetrain wear on Subaru and Toyota engines following a shift to 0W-20 oil, but Honda has been running XW20 oil for fifteen years now and certainly would have designed my engine to take full advantage of it. If I did go up, it'd be to a light thirty such as M1 AFE 0W30 or something to that effect.


Where have you seen this, I'd be interested to read about it. Not just people posting "stuff" on Internet boards, but teardowns and measurements.

 

[Shannow]

Originally Posted By: CATERHAM
Furthermore, all engines consume some oil and I've never seen any evidence that it's due to evaporation even at the 15% level.


Been through this before NOACK isn't about bulk oil consumption, it's about phosphorous transmission to the catalysts...thus the 250C, which is cylinder wall and ring belt temperature.

That being said, viscosity is linked to consumption, particularly at high engine speeds.

 

[tig1]

I use M1 0-20AFE in both engines, and have for years at 10K OCIs. In the Fusion I have done a lot of long trips(19 to Florida and 1 to Maine) driving at all speeds, legal and not so much. No oil use, and engines perform great.

 

[Benzadmiral]

Originally Posted By: aquariuscsm

Absolutely! Texas has some HUGE areas of wide open spaces with hundreds of miles of highway out in the middle of nowhere where you'll be the only car in sight for hours.

I've run through W. Texas from Carlsbad, NM, to San Antonio, and the number of cars didn't pick up until I was approaching S.A. And when I ran to Amarillo a couple of years ago, there were plenty of non-Interstate stretches between Fort Worth and Amarillo where 70 was considered poking along, to judge from the pickups that flew past me when I was running at that speed. A particular song from the '90s comes to mind: