The next engine I see harmed in any way due to the type of oil being used in one of our manufactured fuels will be the first. If I have an engine tuned so lean that the only thing that will save it is Castor oil then shame on me, I deserve to loose that engine. The Klotz oil I use in my gas engines does contain a small % of Castor just like the glow fuel blends. Some of the engines on the market still call for Castor like the Moki but they are also calling for FAI fuel, that's why you should be reading the instructions like Gunner mentioned. Now that I can't get the Power Master with the 18% blended oil I too will be changing brands but it will be whatever I can get from my LHS for the best price, I'm not going to be over thinking the oil issue, they all work just fine.