After years of racing and riding two stroke motorcycles I have tried a lot of different oils.  There are types that smoke a lot, types that separate when they sit to long, and then the types that don't offer the protection that is needed.  When a friend of mine told me to try AMSOIL, I scoffed, after the next engine seizure I figured I would give it a try.  Since I started running AMSOIL I have not had one engine seizure, my bikes run stronger for a longer time, and I noticed that the cylinders were not wearing out. With all that I do not see any reason to change.   Brad Obidowski (HVCcycle)