Oil base stocks are similar in chemical com- ûposition, but it is the additive package that ûmakes the oil. AeroShell’s anti-wear packages ûare the most impressive.

Which oil is really best for your expensive aircraft engine? Or are they all really just the same stuff packaged in different colored bottles and distinguished only by brand names or by advertising claims that may or may not reflect reality?

Frankly, answering these questions is one of the most difficult and expensive research projects The Aviation Consumer has undertaken. Oils for piston aircraft engines serve multiple purposes, including lubricating, cooling, capturing combustion by-products and keeping them in suspension and preventing corrosion when the engine is idle. …