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