I too have wondered why the car engines spec less oil. The only thing I can think of personally is that they spend less time at high throttle/power settings than an airplane engine. Kind of "zoom, zoom, zoom, whereas an airplane engine is WAAAHHHH..."

I think it is also highly likely that a person could run much less the the usual 18% or so oil spec'd for the airplane engines, if you were REALLY careful NEVER to have a lean run. I think other than that, the only real answer will be if/when someone cares to do some extensive testing, and is willing to possibly lose an engine or two "in the pursuit of higher knowledge"...

Reportedly, OS Engines has developed a modified engine, I believe one of their .46 size engines, to run on ethanol with a glow plug. They said that they modified the head and the glow plug to do so. I would like to know more details about what they did, but that was all the article I read in R/C Report said. I contacted the writer, and he didn't have any more info than had been printed.

Time will tell...

AV8TOR