SAE Paper on Engine Wear with 20 wt. oil

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Al

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Before the switch to 20 wt oil there was a paper (pretty sure by SAE) that described shorter engine life of 20 wt as compared to 30 wt oil.

As I call the requirement was that the engine would last 200K miles. I recall that number got reduced to 150K miles. Wish I could resurect that information. It was around 2010.
 
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Before the switch to 20 wt oil there was a paper (pretty sure by SAE) that described shorter engine life of 20 wt as compared to 30 wt oil.

As I call the requirement was that the engine would last 200K miles. I recall that number got reduced to 150K miles. Wish I could resurect that information. It was around 2010.
The question is whether it's relevant with todays engineering/design/materials.
 
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Not necessarily. There have been improvements in coating technologies for bearings.

I think bearing widths have been engineered wider to accommodate thinner oils. Having said that, I run xx-30 as a minimum in my engines.
 
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If you look at the manuals for new cars in places like Australia, they will show a range of oil weights that are compatible based on temperature with the same engine that here they will spec purely at 0W-16/20. So if the oil weight has to do with new bearing width or other design changes, how is this possible?
 
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The ONLY reason for the super thin oils is LABORATORY fuel mileage testing. It has nothing to do with better lubing the engine. EPA requires the oil used in the engines by the manufacturers for EPA fuel mileage testing to be the same as the grade spec'ed in the owners manual. If they can squeeze out a tenth of a mile per gallon more on "x" number of test runs(say 26.5 vs. 26.4 miles per gallon, the EPA lets them average up to claim 27 MPG). Absolutely meaningless in real world driving but means a LOT to automakers. My 2005 CRV "requires" 5W-20 says the owners manual yet the same engine in CRV's in other countries does not recommend such thin oil. Why not? My 2010 Scion XD owners manual says to use 0W-20 but the same vehicle in Europe, the Toyota Urban Cruiser's owners manual recommends 0W-20, 5W-20, 5W-30, 10W-30,15W-40 and 20W-50!
 
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Before the switch to 20 wt oil there was a paper (pretty sure by SAE) that described shorter engine life of 20 wt as compared to 30 wt oil. ...
How much shorter, and under what conditions? When tested in engines designed for what grade? That's just a pointless rumor without more information.
 
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Not necessarily. There have been improvements in coating technologies for bearings.

But what if you are driving a vehicle that was built prior to these "improvements" ?? Like 1998 that was "backspeced " too 5w20?
 
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If you look at the manuals for new cars in places like Australia, they will show a range of oil weights that are compatible based on temperature with the same engine that here they will spec purely at 0W-16/20. So if the oil weight has to do with new bearing width or other design changes, how is this possible?


They might not have 0W-16 in Coober Pedy.
 
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Depending on what test you perform you can make either W20 or W30 look better.

So the fact a paper claims W30 is better doesn't mean anything without looking closely at the test methodology/results.
 
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You guys are overlooking(?) some of the point here, that at two given (differing) temps, a 20wt and 30wt can be identical viscosities. Some of what has gone into lowering viscosity requirements is temperature control and regulation; keeping oil at a given temp to maintain a given viscosity/MOFT is different than regulating coolant temp for optimal combustion, so there are obvious limits that can be achieved, especially since most oil additives require certain temps to activate.

That, plus advancements in oil, bearing, coating, and surface finishing lead me to believe the differences today (even in older engines) would not be as great as expected based off viscosity alone.
 
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How much shorter, and under what conditions? When tested in engines designed for what grade? That's just a pointless rumor without more information.
They used a basic one cylinder test engine. I have that paper here somewhere.
Coatings don't mean much when oil film and/or HTHS is lost.
Yes, bearing size has increased (diameter and width) to accommodate lighter oils along with more resilient piston ring materials and lighter ring tension.
Engine design, clearances, etc. My 1993 Ford 4.9L flat tappet tractor engine was back spec'd to 5w-20.
The test did reveal a difference in wear but proved you could still drive the vehicle to the scrap yard.
 

Al

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How much shorter, and under what conditions? When tested in engines designed for what grade? That's just a pointless rumor without more information.

As I call the requirement was that the engine would last 200K miles. I recall that number got reduced to 150K miles. Wish I could resurect that information. It was around 2010.
You guys are overlooking(?) some of the point here, that at two given (differing) temps, a 20wt and 30wt can be identical viscosities
Its assumed at 100C (engine operating temp). 20 wt. =8 cSt. 30 wt = 10cSt
 

Jackson_Slugger

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What is your opinion on the 20 weight oils at the time of the aforementioned article as compared to 20 weight oils produced today? Just curious.
i think one of these "studies" they "formulated" their own 0W-20 because none were generally available and the only 20W oils then existed as racing oils, which, they either couldn't afford, or were afraid they might thwart their experimenter confirmation bias....
 
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