Originally Posted By: demarpaint
Originally Posted By: Solarent
Originally Posted By: demarpaint
No, not in my case I have two UOA's for the same vehicle were both times the oil moved up a grade.One case was in 5K miles, the other in 6K miles. It did well in the application both times but "thickened." So saying All engines shear oil would be incorrect. There are other examples of oil "thickening" scattered about the UOA section.
You should go back and read my post. Just because you have an oil thickening over the life of the fluid doesn't mean that the engine doesn't shear the oil. It just means you have factors that also thicken the oil at work in your engine as well.
I wasn't referring to you, just making a point. There is a misconception which you alluded to. Many people seem to think oil shears to a "thinner" grade, and that always happens. Thickening is sometimes referred to as oxidation, where oil goes in the other direction. Bottom line oil can go up or down a grade, or more.
But what you have is thinned, oxidized oil going up a grade. Obviously, this is not a good thing. When I lived a long time ago, in a far, far galaxy, this is something I would see occasionally in testing. Usually it was from diluted, oxidized oil. So, what you have is fuel and pentane insolubles meeting or exceeding a viscosity, not oil(broadly speaking). But is that what you really want running around in your engine?