10-07-2013, 09:03 AM
Good logic, but it doesn't take into account the primary reason that aircraft engines use special oil. It's not because aircraft oil is of higher quality. It's because aircraft engines, by design, burn a lot of oil. Unlike modern cars and motorcycles, they're built to relatively loose tolerances and are expected to burn a certain amount of oil the gets past the rings. In fact, if your airplane engine doesn't burn any oil, you've got (or will soon have) a problem.
Aircraft oil has a different type of additive package than modern car/bike oil. The detergents and other additives in modern car/bike oils work great to keep our engines clean and keep oil from breaking down. Unfortunately, those additives, when burned in the combustion chamber, leave an ashy residue. Because of that, aircraft oil must do without those additives. Instead they use what is called an "ashless dispersant" (a.k.a AD oil). That is an additive that will not leave an ash residue when burned. The dispersant aids in holding contaminants suspended in the oil and carrying it to the screen or filter.
In sum, aircraft oil cannot use all of the latest spiffy additive packages that have been created for car/bike oils over the last decades because of the ash issue. AD oil is what we have to use because our airdraft engines burn a significant amount of oil.
I happen to use Phillips X/C 20w-50 in my plane and have for decades. It hasn't changed much over the years. For my bikes, there's no way I'd pass up a technologically modern oil for an oil designed for oil burning engines of 1950s/1960s technology.
BTW, aircraft engine manufacturers require that oil be changed every 25 or 50 hrs. of operation (lower number if you have a screen instead of a filter). Most of us tend to change it sooner than required. If you put an hour meter on your bike, I think you'd be alarmed at how often you'd have to change the oil.