RET,
I don't think we actually need to get that technical to answer your question. In fact, I think this whole subject gets so confusing cause we try to get too technical.
I'll make one of those blanket statements now which you're not supposed to make if your a technical kind of guy, but I challenge anyone to refute it.
<font color=red> In 30+ years of fixing broken cars and old construction equipment I have never seen a oil related failure that was caused by using the wrong oil </font color=red>.
Plenty of failures from not having enough oil, or not changing it often enough. But not a one from using conventional oil in place of synthetic, or synthetic in place of conventional, or using a different viscosity, or mixing brands and types.
Viscosity is the only real difference, and it's main affect is causing a cold engine to be harder to start if you're using too high a viscosity. Here in texas, it's hard to get a engine cold enough for this to matter, no matter how high the viscosity.
All modern oils exceed the requirments placed on them by such a margin, that when we start talking about obscure differences in cold flow properties, long term breakdown of additives used to achieve multi-viscosity, reaction to carbon content in diesel fuels, ability to hold contaminants in suspension, clingability, film shear strenght, ect. ect. ect.,,,we might as well be talking about how many hairs on a gnat's a**.
I keep a copy of the Consumer Reports study jbs mentioned in my waiting room to show customers when they ask about oils. But most don't ask, they come to me already decided. I consequently keep in stock a bunch of different oils to satisfy their advertising induced prejudices.
But, my opinion, there's not a hill of beans difference in their ability to satisfy the requirments of normal users. The exception being fleet operator who measure profit or loss in fractions of cents per mile, or special users with requirments for extreme longevity or continous operation.
Change it often, keep it full. That's my advise.
Dave Perry