I would stay away from castor for that application. Any high end ester synthetic is going to give you excellent protection and performance. Motul 800 2T, Bel-Ray H1R, or Maxima K2 are all excellent. I run all my two-strokes on Motul 800 2T at 32:1 mixed with VP racing T4 fuel. I love VP's SEF, and they use a Motul product in that, but I haven't been able to find out which Motul oil specifically from either company. Regardless, it gets expensive and cumbersome to buy quarts of fuel, so buying a 5 gallon of VP T4 (96 octane and no ethanol) is my preferred method. I run this mix in 250R quad, my 395XP, and Jonsered 2172 saws, and even some vintage Mac saws. I have never seen any downside to 32:1, and alot more oil is present in the crank area which makes me feel good about the protection. The piston crown only ever has a slight film that is never hard. My dad runs the same fuel mixed 50:1 with Stihl Ultra, and the residual film is not as convincing upon teardown on his as with the 32:1 mix. My saws smoke no more than his and they run great.