Is there a slight bump up in MPG as oil shears?

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Originally Posted By: kschachn
When does oil shear?


Check out UOA's from EB engines. They'll shear oil from a 5w30 to a 5w20. It's the whole reason Ford back spec'd most of them to 5w30.
 
Originally Posted By: kschachn
When does oil shear?
Oil [mulit visc oils] shears between the moving parts as the engine is running
 
This came up during a recent discussion.

Oil can shear slightly with use, but as the more volatile components of oil evaporate with use, it has a thickening effect.

So the net effect is more or less 0.
 
Originally Posted By: Reddy45
This came up during a recent discussion.

Oil can shear slightly with use, but as the more volatile components of oil evaporate with use, it has a thickening effect.

So the net effect is more or less 0.


I didnt think of thickening.
 
another reason to use better oils + real synthetic groups IV + V are the BEST. less shear + less viscosity improvers that get used up + thicken oils!!
 
An often made statement, but as far as I've seen without merit. SonofJoe has repeatedly stated that modern viscosity improvers are very stable and are highly resistant to shear degradation. Also, how would you even know if the typical Blackstone analysis that shows viscosity loss is due to shear or fuel dilution?

Originally Posted By: benjy
another reason to use better oils + real synthetic groups IV + V are the BEST. less shear + less viscosity improvers that get used up + thicken oils!!
 
Originally Posted By: Reddy45
This came up during a recent discussion.

Oil can shear slightly with use, but as the more volatile components of oil evaporate with use, it has a thickening effect.

So the net effect is more or less 0.

There are 100's of UOA's on here alone that show oil sheared out of grade(little or no fuel in oil) and on the motorcycle section you will find most bikes with a shared transmission get oil thats sheared out of grade in 4000 miles or less. Sometimes a lot less miles, my old R6 would only get 2500 miles on its oil before it would shear and make shifting real notchy.

ROD
 
I keep track of my oil level carefully, and always see the consumption starts low, then starts to increase after about 300~400 miles are put on the oil. All I can think is that oil is shearing down some which increases the oil consumption enough to see it.
 
Originally Posted By: SirTanon
It's time to stop fat shaming our oil. Why does it HAVE to be thinner?

Thin is in!
 
because trees and plants give off oxygen during photosynthesis and you will have better athletic performance if you work out outside in the daytime versus at night.

same logic
 
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