Regarding the outboard oil use in aero engines. Outboard oil was designed around an engine having a water jacket that was constantly moving a cooler fluid through the engine to moderate heat. The oil does not have to be as good at heat collection as one used in an air cooled engine.

As for using engines many years without ill effect, one must evaluate the different between years of use and hours of yuse. Then you have to factor the use time "continuos" and the engine loading. I know that many feel that adding a propeller "loads" an engine, but to what level of a load? Fine pitched props don't provide as much load as a coarse pitch. Large diameter props load more than small diameter. Adding a generator adds even more load. Heavy planes load more than a light plane.

Lots of factors influence what is done to and with an engine but most people don't have a clue what is going on with their propulsion systems. They've never had to know, therefore they never learned. In the last 10 years or so it's all been about power to weight ratios. if you had more than 1-1 the plane would always accellerate straight up. What happens when that power to weight falls to full scale, production, light aircraft levels of .2 to .4-1? Suddenly one needs to know and pay attention to what is taking place in their engines.

The hobby manufacturers made the equations easy. You didn't need one, all you needed was an aircraft weight and an approximate engine size as provided by the kit manufacturer. That's still more than some currently understand.