My dad, who was an engineer for Mobil, in the days when detergent was just being added to oils, said that the best motor oils had most of it's molecules at the specified viscosity, but also contained a mixture of molecules that were very short, so as to act as penetrating oil, and very long, so as to act as a motor honey, and not drain off of cams and cylinder walls. In those days, STP also had a lot of zinc (dialkyldithiophosphate, [ZDD]) in it, and we didn't have catalytic converters to burn out, STP thus has a lot less zinc in it, these days, which can be problematic for air cooled engines, though I had a friend who ran several O-470's through to overhaul with almost no wear on full strength STP in the oil. My thinking is, that a little STP, or generic motor honey, would be helpful in aircraft engines...(and, some MMO).but, don't quote me....I'm leaving for Zeta Reticuli in the morning....
*Although, if you are running a multi-vis oil, you have a thin oil, (the lower number) mixed with motor honey...already....
*What oils seem to NOT have in them, are enough anti-oxidents....which is where Cam-Guard comes in.....