0W-20 in 5W-20 Engine

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Where does VII affect the viscosity the most… At 40 C or 100 C? When oil shear happens what happens to the viscosity at 100 C?

Maybe this video is too simple cause they use straight lines and not correct except for the two points 40 c and 100 c.

 
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ZeeOSix

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Where does VII affect the viscosity the most… At 40 C or 100 C? When oil shear happens what happens to the viscosity at 100 C?

Maybe this video is too simple cause they use straight lines and not correct except for the two points 40 c and 100 c.


The lines are straight because the viscosity scale is logarithmic. Example.

1654626628129.jpeg


1654629011246.jpg
 
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ZeeOSix

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Wonder what that line would look like with VII?
Those straight lines are the viscosity vs temperature with VIIs in the oil. The slope of the straight line will change as the amount of VIIs is changed - just like shown in the video you linked in post #41. If the viscosity scale was not logarithmic, the viscosity vs temperature graph would look like these (example).

If you plotted the graph below with a logarithmic viscosity axis, it would all be straight lines like shown in post #42.

1654627812718.png
 
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ZeeOSix

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When oil shear happens what happens to the viscosity at 100 C?
When oil shears, there is temporary viscosity loss, and there is permanent viscosity loss which happens when the VIIs break into smaller pieces. Viscosity decreases when oil shears - the higher the shear rate, the more the viscosity loss. The amount of permanent shear depends on the VIIs and of course how long the oil is ran and exposed to shearing.

1654634966478.jpg
 
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I think burgessdg "flow rate ... when hot" comment is a bit lost. Maybe he uses a paint viscometer - a cup with a hole in it. The other comments about base stock grade and VM action go back to the beginnings of Multi-grade "All Season" lubricants. The formulation is not so simplistic nowadays. - Ken
LOL, maybe there should be a section for the Doctors, and one for the patients. I fail to see how my statement was wrong from a "practical" standpoint. But hey, I have failed with Engineers before and I will fail again. Most of us are on the practical side.
 
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0W-20 and 5W-20 are one-for-one replacements. Honda and Toyota backspeced all their 5W-20 cars for 0W-20 and either Castrol or SOPUS recommends 5W-20 applications needing D1G2/G3 to use their 0W-20 oils.

However, 5W-20 oils will use less VII in some cases and even between oils of the same brand and family, the composition will vary somewhat. Take the case of M1AFE and M1EP 0W-20. The former is mostly GIII GTL with a little PAO or ester added in to achieve certain performance targets or as an carrier for the add pack, the latter has 70-80% PAO.
 
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LOL, maybe there should be a section for the Doctors, and one for the patients. I fail to see how my statement was wrong from a "practical" standpoint. But hey, I have failed with Engineers before and I will fail again. Most of us are on the practical side.
Well, I suppose practically speaking, and Ostwald viscometer uses "flow rate" through a restriction to measure viscosity. Maybe you are ahead of many a layperson here who think that a Brookfield-style viscometer is more commonly used to measure oil viscosity at operating temperature :)

As far as the confusion with Multi-grade all season oil grade labeling, it certainly can lead to questions and confusion, and then add that most auto parts counter guys and mechanics still use the "It's a 5 weight oil when cold and a 30 weight oil when Hot" explanation, which doesn't necessarily help the average Joe any more. And now we can add rampant internet lore to further confuse .. most anything.

Back to the 1950's.

Many cars recommended a SAE 10W oil for winter use. This was a solvent de-waxed oil with good winter pumpability. We are staring to see 12V systems and starters, so crank-ability wasn't as important as it once was.
Now, the same car might recommend a SAE 20 or 30 motor oil for temperatures comfortably above freezing - a summer lube. But, be aware there are differences between an SAE 20 and an SAE 20W lubricant.

At some point in the late 50's Oil Co's started marketing All-Season Multi-Grade motor oils that could be used winter or summer. This is where we are now, ubiquitous among passenger car lubricants.

I hope this journey was a bit fun !

Under-hood oil grade recommendation sticker from a 1955 Ford Fairlane pushrod V8

Ford_Y_block oil  requirement sticker..jpg


Vintage Multi-Grade oil Can
marathon all season motor oil.jpg
 
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2020 Ford F-150 Lariat 4x4 with 5.0L. 60,000 miles on it.

Can I use 0w-20 in it when it calls for 5w-20? Have a lot of 0w-20 in oil stash for wife’s car, and was curious if this would work without causing any issues.

Daily driver. 20 miles to and from work. A lot of highway miles. Light towing occasionally. S/E part of US.

Thanks so much!

Yes.

Yes you can.

And the engine will be OK!
 
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2020 Ford F-150 Lariat 4x4 with 5.0L. 60,000 miles on it.

Can I use 0w-20 in it when it calls for 5w-20? Have a lot of 0w-20 in oil stash for wife’s car, and was curious if this would work without causing any issues.

Daily driver. 20 miles to and from work. A lot of highway miles. Light towing occasionally. S/E part of US.

Thanks so much!
Yes
 
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LOL, maybe there should be a section for the Doctors, and one for the patients. I fail to see how my statement was wrong from a "practical" standpoint. But hey, I have failed with Engineers before and I will fail again. Most of us are on the practical side.
It's wrong from both a practical and a technical aspect.
 
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