Why do people run higher weight oil in summer?

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Originally Posted by RayCJ
Here's a couple direct quotes from a Mazda3 owner's manual. Read between the lines and it says, 0w-20 gives better fuel economy and 5w-20 or 5w-30 lubricate the engine better. FWIW, I use the USA recommended viscosity year round.




You came to the conclusion you wanted. The term is confirmation bias I believe.
 
It seems like a constant argument between the people who blindly trust whatever the oem God's tell them to use (why even come to bitog if all you ever believe or recommend is to follow the oem recommendation for oil grade and oil change intervals (especially the second one).

Some of us won't ever be convinced that the manufacturer always has our best interests in mind and nothing else.

There are also people who think of a vehicles "lifetime" as being like 5-10 years. Then there are people like me driving 35 year old vehicles. If I bought a new vehicle today (which cost more than every vehicle I bought in the past 16 years combined) then I would be trying to make it last as long as the cars I'm driving now.

For the record when it comes to giving other people advice I usually recommend following the manufacturer recommendation. But these average people aren't trying to get 300k miles or more from their vehicles. If someone is asking on here it's because they're trying to do the absolute best for their vehicle and not just "good enough".
 
And they face the buyer on Monday who wants lots of power off less gas … and CAFE on Tuesday who wants MPG ~ period - and did not buy the vehicle and not concerned about longevity …
The Hemi thread is an example …
 
*My belief is in some vehicles 5W20 weight is more about skating by CAFE and MIGHT be marginal in the summer (especially towards the last 1/3rd of an OCI) ... 5W30 errors more towards offering a buffer in those conditions where shear , fuel dilution , viscosity break down , etc. may come into play .
Originally Posted by Brian553
The engine oil temperature is greater in summer. This is taken into account for an automaker in both engine design and setting their maximum warranty--pairing a grade to the engine. However, the warranty period and terms of acceptable conditions induced by wear in that warranty period may not be to the satisfaction of some consumers, particularly those found on this site. I don't know of many engines that have had catastrophic failure when the end user followed the manufacturer's specified grade, oci, and appropriately retired/ replaced their oil filters, both during the warranty period and long after (and made sure that it was never under-filled.)
 
I've used nothing but recommend weights by the manufacturer. No issues to date. Why try to reinvent the wheel. Unless a uoa says other wise.
 
Originally Posted by dave1251
Originally Posted by Dave9
Originally Posted by Whammo
I have seen a lot of people recommend running a 5w30 instead of a 5w20 in summertime. As far as I know, the engine operating temp isn't going to be higher in the summer. If the manual says 5w20 is fine year round, why mess with it?

The manual is about fuel economy numbers mandated by the EPA/nonsense.

As far as you know, is wrong. The engine operating temp is higher in summer. Realize that there is a delayed reaction. The thermostat is set for a temp, but the cylinder temp is higher when the ambient is.

The radiator fan is set for a temp, but again it is a delayed reaction. It matters less today with modern oils, especially synthetic, but ultimately there is no magic here.

The base oil weight is what dictates steady state operation. The -V weight just dictates the cold flow. The second number is what you pick for the operational environment at normal ambient and running temp.

Ignore this if you wish.



It's not about ignoring anything. The OEM states what grade to use. I have used other than the recommended grade because I know using a 30 grade where a 20 grade is recommended because extra human hair thickness won't hurt anything. All you stated is 20 grade recommendation is for better fuel economy which is true but there is no evidence using a 30 grade provides longer engine life over a 20 grade.



Well a couple months ago I did my spring OCI. Most of my driving is in Severe service city and secondary roads. My car delivered its highest MPG ever in this service with 10w-30 Havoline Pro DS 36 MPG +. This is one person that does not believe the CAFE thinner oil higher MPG myth.

Final cost of my oil is the determining factor 99% of the time. I almost change name brands every OCI. Oh and on occasion I use HM because it was the cheapest. The bottom line is all oil is oil.
 
Running a thicker grade in summer goes back to the straight grade days. There is no need to change anything with modern oils.
 
Oh, I guess these OEM's and oil companies never dyno tested with sophisticated instrumentation …
and never field tested with QAQC boundaries …
You should call them about the 0w20 myth …
 
Originally Posted by rooflessVW
I don't run a thicker oil in the summer. I run a thinner oil in winter.
Any reasons for that? I hope I can ask you without hurting your feelings. Another profanity-laced tirade and/or profane graphics like you posted recently, would not further the purpose of these forums. You understand that, right? Of course, you didn't get banned from your cursing & posting graphics before, so it must be OK to do, according to the Moderators.
 
I've observed very minimal change in operating oil temperature with changes to ambient temperature. I used 10w-30 in my '66 Mustang 289 engine and it would stay around 220*F oil temp cruising down the highway regardless if it was 20*F in January or 100*F in July. The oil would reach 220*F quicker during the summer, but that's a good thing. I see no reason to run a higher grade oil in the summer.
 
Originally Posted by 4WD
Oh, I guess these OEM's and oil companies never dyno tested with sophisticated instrumentation …
and never field tested with QAQC boundaries …
You should call them about the 0w20 myth …


Wait, are you suggesting there's data to support those mfg recommendations in the event the mfg needs to fend off some class action lawsuit alleging they knowingly recommended the wrong oil type/grade?

That's just crazy talk......‚
 
Originally Posted by oil_film_movies
Originally Posted by rooflessVW
I don't run a thicker oil in the summer. I run a thinner oil in winter.
Any reasons for that?

Because a 50 is a little clickity-clackity on cold starts if I have to leave the car outside for a few hours, and I don't get any track time during the colder months any way. Not that I think you really want to know beyond having a reason to start another argument.

I deleted the rest of your post because it didn't add anything to the discussion, and I'm not going to let you bait me again.
 
In my 6.6L duramax (more than one Durami?) I typically run 5W40 in the winter, 15W40 spring & fall and SAE 40 in the summer.
Perhaps I should switch to 15W50 spring, summer and fall?

BTW, the only Duramax that listed XW30 as an optional grade was my first, a 360 HP LBZ.
The 2 others: LML and L5P only approve 5W40 and 15W40,
When ambient allows, 15W40 is the preferred grade.
 
Originally Posted by eljefino
Originally Posted by pbm
Because they want to use up their stash of CLEARANCE oils.


LOL the real answer. And mine.


Me three. For the Mazda I've built a stash of 0w20, 5w30 and 10w30 purchased from various clearance/sale/rebate events. In the winter I always use 0w20, but now that my warranty is up I've started dipping into the 5w30 for summer use. When that is gone, I'll mix 0w20 and 10w30 (1.5 to 1) for summer use.
 
Originally Posted by Whammo
I have seen a lot of people recommend running a 5w30 instead of a 5w20 in summertime. As far as I know, the engine operating temp isn't going to be higher in the summer. If the manual says 5w20 is fine year round, why mess with it?


I wouldn't in a newer vehicle, especially under warranty. But some cars burn oil as they age...
 
Are you talking about the vehicles that specifically allow thicker oils in the owners manual, for example for my girlfriend's 2013 Sonata? It got 5w30 last time, instead of 5w20. The manual says it's fine.
 
With a fuel diluting (albeit yes, less likely in the summer), small sump capacity (4.2 quarts), TURBO direct injected engine of 1.6 liter displacement, with a marginal factory cooling system, and an aftermarket, not vented skid plate, and no hood vents, running as hard as I tend to push it, yeah, I WILL go up to a medium weight HTHSV 5W-30 in the summer.
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(ESPECIALLY since this same EXACT car's manual in Europe/rest of world explicitly allows for this.
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)
 
Within the next 2-3 days I will be stepping up from 0w-20 to 5w-30 in the 2016 Accord. The reasons for this, listed in order of decreasing importance, include all of the following:

  • Poor UOA results showing double the levels of Al and Fe for this engine
  • Fuel dilution due to direct injection, leading to lower operating viscosity
  • Hot weather - this vehicle will be running 100 miles per day in temperatures between 75 and 105F.

As you can see, summer temperatures are a factor, but a small one. Most vehicles will exhibit higher oil temperatures in the summer months. Six months from now I should have some objective data to share.
 
Originally Posted by dave1251
Originally Posted by RayCJ
Here's a couple direct quotes from a Mazda3 owner's manual. Read between the lines and it says, 0w-20 gives better fuel economy and 5w-20 or 5w-30 lubricate the engine better. FWIW, I use the USA recommended viscosity year round.




You came to the conclusion you wanted. The term is confirmation bias I believe.


All over the world except the USA (and maybe canada) Mazda 3 manual says its ok or recommended to use 5w30.
Again, makes much more sense choosing an oil for your climate, then choosing an oil by brand when something like Super Tech, lubricates just as good and anything else in the same API. :eek:).
 
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