1) Aviation and automotive oils are very different. I wouldn't use an additive in one that was meant for one in the other unless the manufacturers (of the oil, the additive, and the engine) say its OK. Maybe in a Chevy where if it doesn't work you just throw the engine away and get a new one for fifty bucks, but not in a Benz.
2) Don't think FAA or aviation means "great". It doesn't. The latest and greatest piston aircraft engines were designed in the 1960s, have pushrods, run a whopping 8.7:1 compression ratio (on 130 octane!), and are cast in sand molds. Did I mention the magnetos? Airplanes are all about reliablility, not cutting-edge technology, as least not as long as the FAA makes it so hard to innovate in the field of aviation. I guarantee you a thousand times more money has gone into researching car engine additives than it has for aircraft.

Matthew
87 560SEL 130K
Half-built airplane next to it in the garage