RE: using drug store castor oil?
I use fuels that are part caster (Omega is one). Used to be nervous because articles in the magazines acted like all commercial fuels didn't contain enough oil, and also recommended breaking in engines with added caster. I quit worrying about all this nonsense, and I have wonderful success with my two cycle engines, and they last a long time. I am retired, and fly a lot, and my engines are lasting an incredably long time (they must make them better than they used to). I don't even use any after run oil when I'm through flying (although I do start the engines with the fuel line removed). I have no experience with 4 cycle or gas engines, but if you are talking about two stroke, relas and enjoy flying with commercially available fuel.