Why Do Knowledgeable Folks on Here use 20 wt Oil

[Patman]

And also just found out another buddy with the same GR Supra tacking it....run Motul XCess 5W40. A true thin/thick Supra battle!

The 0w20 guy will be faster because he’s making 2 extra horsepower

 

[TiGeo]

The 0w20 guy will be faster because he’s making 2 extra horsepower

I'll be taking notes...

 

[alcyon]

I live in Malaysia, and my wife has a 2021 Mazda Cx-8. The dealer uses Shell Helix 5W-30. I bet in the US it is 5W-20....

 

[Astro_Guy]

My new 2025 Toyota Camry is a 2.5 L hybrid and calls for 0W-8 GLV-1 oil. My wife takes it for many short trips(5 miles each way to work and 2 miles each way to supermarket with occasional once monthly hour long trips). I already ordered Amsoil 0w-8 for the first 5,000 mile oil change. I will send a sample to Blackstone labs. Other than doing the 5,000 mile changes instead of 10,000 mile changes, what’s an owner to do? I plan to keep the car for ten years-indeed I already purchased a 10 year/100,000 mile warranty.

FWIIW - My family ran a 2010 Prius for 210K miles on 10K OCIs at the dealership. It may be a noble thing to run one or two 5K OCIs while breaking in the engine, but your Toyota is likely to take the recommended 10K OCI in stride. Get the UOAs as you intend to rather than taking any post here based on faith alone.

 

[DemoFly]

I never understand threads like this because there's a UOA forum and that data tells the truth.

 

[Glenda W.]

The 0w20 guy will be faster because he’s making 2 extra horsepower

Unfortunately the problem with this situation won’t show up until an owner or two after. At some point someone may tear into the motor and discover the upper rod bearings worn through a layer or two, but not spun. Eventually a slight rod knock may be present but the engine may run perfectly fine.

 

[kschachn]

I never understand threads like this because there's a UOA forum and that data tells the truth.

If only that were the case. Singular uncontrolled UOA aren’t nearly as useful as many imagine them to be.

 

[Patman]

Unfortunately the problem with this situation won’t show up until an owner or two after. At some point someone may tear into the motor and discover the upper rod bearings worn through a layer or two, but not spun. Eventually a slight rod knock may be present but the engine may run perfectly fine.

Truth! I would never run a 0w20 if I was going to the track, in fact I would not run anything less than something with a 3.5 HTHS.

 

[TiGeo]

Truth! I would never run a 0w20 if I was going to the track, in fact I would not run anything less than something with a 3.5 HTHS.

I agree and it's why the second guy runs the Motul 5W40. I suspect however for casual track use it will make zero difference. Every weekend? Sure.

 

[ARCOgraphite]

Casual Track use

Sounds funny.

 

[2strokeNorthstar]

What is this 3 factor bearing graph that you speak of like its eveyday knowledge? Is it the 3 ball Amsoil test that proves nothing in the real world?

 

[Glenda W.]

Here’s a good example(not mine) of upper rod bearing wear. Surprisingly I’ve witnessed about this much wear on engines with no audible indications. Eventually they will get beaten to death and develop rod knock.

 

[Shel_B]

Here’s a good example(not mine) of upper rod bearing wear. Surprisingly I’ve witnessed about this much wear on engines with no audible indications. Eventually they will get beaten to death and develop rod knock.

View attachment 266514

I want to be clear, are you suggesting that a thicker oil would have reduced or eliminated that wear?

 

[spasm3]

Here’s a good example(not mine) of upper rod bearing wear. Surprisingly I’ve witnessed about this much wear on engines with no audible indications. Eventually they will get beaten to death and develop rod knock.

View attachment 266514

Rod bearing uppers? Looks like some lugging, is this a manual transmission vehicle?

 

[TiGeo]

Casual Track use

Sounds funny.

I'd call doing a 2 day event once a year casual vs say 10 days+. Not everyone is out 10/10 here with peaked oil temps etc.

 

[Brian123]

Here’s a good example(not mine) of upper rod bearing wear. Surprisingly I’ve witnessed about this much wear on engines with no audible indications. Eventually they will get beaten to death and develop rod knock.

View attachment 266514

Is this a pic from an Engine that was run on Shell Rotella, this pic looks like something I have seen here on this Board a while ago.

 

[Shel_B]

Rod bearing uppers? Looks like some lugging, is this a manual transmission vehicle?

You brought up a very good point. I was taught not to "lug" an engine, and I always downshift, even with an automatic trans, when going up a hill so the engine can run freely under a lighter load.

I've never examined bearings before, but your suggestion looks and sounds reasonable.

 

[Glenda W.]

I want to be clear, are you suggesting that a thicker oil would have reduced or eliminated that wear?

Yes. Upper rod bearing wear is one of the first indications when to low viscosity is being used in severe service. GM’s temporary fix was going up a grade. Eventually a TSB was released with an upgraded fan clutch to get oil and water temperatures back in check on trucks used for plowing. The plow itself was obstructing air flow even at low speeds.

 

[Glenda W.]

Rod bearing uppers? Looks like some lugging, is this a manual transmission vehicle?

This is upper rod bearing halves. Again not my picture, just using as an example of what I’ve seen at the dealership years ago.

 

[Glenda W.]

Is this a pic from an Engine that was run on Shell Rotella, this pic looks like something I have seen here on this Board a while ago.

No idea. Just using the pic as a good example of upper rod bearing wear.