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Do Manufacturers Assume Loss of Grade? #5464746 06/28/20 09:34 AM
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Gene K Offline OP
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I've been thinking about the tendency of oil to shear in some applications. I was trying to figure out why a manufacturer would spec a 5W-30 over a 5W-20 if they both came out of the crankcase at 8.6 cSt.

Do manufacturers assume a one grade loss in use?
IE 5W-30 will be a 20 Grade and 5W-20 will be a 16 Grade?


Gene

2014 Mustang GT 5.0 SC - 675 bhp
ST Synthetic 10W30 / FL500S

2018 F150 4x4 3.5 EB
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2018 Lincoln MKX 3.7
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Re: Do Manufacturers Assume Loss of Grade? [Re: Gene K] #5464762 06/28/20 10:00 AM
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JohnnyJohnson Online Content
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LOL they don't assume anything you bought it and now its your problem!


2004 Corolla 140708
Out: Pennzoil Platinum HM 5W-20 ST 4386
In: Valvoline Synpower Full Synthetic 5W-30 Purolator PureONE
2006 Duramax 77117
Out: T6 5W-40 XG9100 73909
In: Rotella Dino PH9100 11-3-19
Re: Do Manufacturers Assume Loss of Grade? [Re: Gene K] #5464769 06/28/20 10:06 AM
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Like most things oil...does it really matter as long as it meets specs going in and it's changed at an appropriate OCI? This forum has plenty of UOAs with significant fuel dilution, low to out of grade viscosities and no apparent issues with the engine.

Last edited by PWMDMD; 06/28/20 10:06 AM.

Current: 2020 Toyota Tundra Platinum (PP 0W-20 and Toyota OEM Filter) and 2019 Lexus RX 350 (PP 0W-20 and Toyota OEM Filter)
Re: Do Manufacturers Assume Loss of Grade? [Re: PWMDMD] #5464781 06/28/20 10:26 AM
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Gene K Offline OP
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Originally Posted by PWMDMD
Like most things oil...does it really matter as long as it meets specs going in and it's changed at an appropriate OCI? This forum has plenty of UOAs with significant fuel dilution, low to out of grade viscosities and no apparent issues with the engine.


So your saying the manufacturer picked the grade by flipping a coin?

Last edited by Gene K; 06/28/20 10:26 AM.

Gene

2014 Mustang GT 5.0 SC - 675 bhp
ST Synthetic 10W30 / FL500S

2018 F150 4x4 3.5 EB
OEM Oil & Filter

2018 Lincoln MKX 3.7
OEM Oil & Filter
Re: Do Manufacturers Assume Loss of Grade? [Re: Gene K] #5464786 06/28/20 10:36 AM
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UncleDave Online Content
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Of course. Thats call figured into the OCI and recommended grade.

The hysteria around 20 grade is amusing because many have been effectively driving around with sheared and diluted 20 that started at a 30- for decades.

UD


Uncle Dave
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Re: Do Manufacturers Assume Loss of Grade? [Re: Gene K] #5464788 06/28/20 10:37 AM
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PWMDMD Offline
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Originally Posted by Gene K
Originally Posted by PWMDMD
Like most things oil...does it really matter as long as it meets specs going in and it's changed at an appropriate OCI? This forum has plenty of UOAs with significant fuel dilution, low to out of grade viscosities and no apparent issues with the engine.


So your saying the manufacturer picked the grade by flipping a coin?


I'm saying whatever their reason for one grade or another have you ever seen definitive proof it really matters? How many "discussions" do we suffer through on here with respect to "Oh my God engine X used to be spec'd for 5W-30 and now purely because of CAFE it's spec'd for 0W-20 and the sky is falling". Then mile after mile and UOA after UOA life goes on seemingly without any issues.

I think BITOGers, in general, try too hard to dissect out the nuance in oil choice that 99% of the time makes no appreciable difference. It really doesn't have to be any harder than following the manual for grade, certs and OCI. Then again, if we just did that, half of all posts here could be deleted.


Current: 2020 Toyota Tundra Platinum (PP 0W-20 and Toyota OEM Filter) and 2019 Lexus RX 350 (PP 0W-20 and Toyota OEM Filter)
Re: Do Manufacturers Assume Loss of Grade? [Re: Gene K] #5464802 06/28/20 10:51 AM
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This is a concern that comes up with wet clutch motorcycles. In the most severe case, I've seen a UOA of a bike that sheared 10W60 down to a 30wt (KTM I think?).

Not sure if it really matters as long as the wear metals stay within safe ranges... the only viable "fix" is to change the oil every 1K or something but that's just impractical and expensive.

Re: Do Manufacturers Assume Loss of Grade? [Re: Gene K] #5464818 06/28/20 11:31 AM
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They don't assume anything, they do hundreds upon hundreds of tests and determine and dissect actual results

Re: Do Manufacturers Assume Loss of Grade? [Re: Jimmy_Russells] #5464880 06/28/20 12:58 PM
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Gene K Offline OP
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Originally Posted by Jimmy_Russells
They don't assume anything, they do hundreds upon hundreds of tests and determine and dissect actual results


Which is why I am asking, what is the advantage of 5W-30 over 5W-20 if they are the same viscosity after a couple of thousand miles? All I could come up with is a worse case assessment that some formulations of 5W-20 might shear to a 16 grade.

Last edited by Gene K; 06/28/20 01:02 PM.

Gene

2014 Mustang GT 5.0 SC - 675 bhp
ST Synthetic 10W30 / FL500S

2018 F150 4x4 3.5 EB
OEM Oil & Filter

2018 Lincoln MKX 3.7
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Re: Do Manufacturers Assume Loss of Grade? [Re: PWMDMD] #5464887 06/28/20 01:06 PM
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hallstevenson Online Content
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Originally Posted by PWMDMD
I'm saying whatever their reason for one grade or another have you ever seen definitive proof it really matters? How many "discussions" do we suffer through on here with respect to "Oh my God engine X used to be spec'd for 5W-30 and now purely because of CAFE it's spec'd for 0W-20 and the sky is falling". Then mile after mile and UOA after UOA life goes on seemingly without any issues.

I think BITOGers, in general, try too hard to dissect out the nuance in oil choice that 99% of the time makes no appreciable difference. It really doesn't have to be any harder than following the manual for grade, certs and OCI. Then again, if we just did that, half of all posts here could be deleted.

"Like, like, like, like"

Re: Do Manufacturers Assume Loss of Grade? [Re: Gene K] #5464890 06/28/20 01:09 PM
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30 grade oils sheared down in the 80's. But do the modern 30's shear down in the absence of fuel dilution?


13 elantra 84k 5w30 synpwr
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Re: Do Manufacturers Assume Loss of Grade? [Re: Gene K] #5464892 06/28/20 01:09 PM
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hallstevenson Online Content
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Originally Posted by Gene K
Do manufacturers assume a one grade loss in use?

I'm sure they factor in far more things than most here can even dream of and they realize, they're non-factors. On top of many moving from 30 weight down to practically-water-20-weight oil, they are extending the oil change intervals (oh my !) and with what consequences ? None to speak of in all reality. If there's one thing people do agree on, engines are lasting longer than ever.

Re: Do Manufacturers Assume Loss of Grade? [Re: spasm3] #5464896 06/28/20 01:14 PM
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Originally Posted by spasm3
30 grade oils sheared down in the 80's. But do the modern 30's shear down in the absence of fuel dilution?


Yup - certain mills are worse than others.

DOHC V8's with DI tend to be hard on oil. (even my non DI Titan shears oil pretty hard)

feet and feet of chains, multiple sprockets, tensioners, and a high pressure DI pump - all combine to beat the snot out of oil.

UD


Uncle Dave
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Re: Do Manufacturers Assume Loss of Grade? [Re: spasm3] #5464900 06/28/20 01:17 PM
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Gene K Offline OP
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Originally Posted by spasm3
30 grade oils sheared down in the 80's. But do the modern 30's shear down in the absence of fuel dilution?


I've definitely seen some engines that call for 5W-30 where you can't tell by analysis whether they started with 5W-20 or 5W-30. Essentially the same end viscosity. Of course given some of the UOA it's debatable whether they have appreciable fuel dilution.


Gene

2014 Mustang GT 5.0 SC - 675 bhp
ST Synthetic 10W30 / FL500S

2018 F150 4x4 3.5 EB
OEM Oil & Filter

2018 Lincoln MKX 3.7
OEM Oil & Filter
Re: Do Manufacturers Assume Loss of Grade? [Re: JohnnyJohnson] #5464903 06/28/20 01:19 PM
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Originally Posted by JohnnyJohnson
LOL they don't assume anything you bought it and now its your problem!

Lol. Best reply ever and so true


2009 Nissan Maxima
2011 Nissan Maxima
2004 Honda Odyssey
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