I'm just getting back into the hobby after a 30 year layoff. I bought a new Magnum 52 four stroke for my first plane and the break-in instructions is use a minimum of 20% castor, don't use synthectic. 10% max nitro. We live in a hobby deprived area, and the three stores here sell paint balls and car fuel. I finally found a quart of 10% nitro with 17% Caster/synthecic oil. A bit low on Castor so I went down to the local drug store and picked up a 6 oz bottle of Castor oil, the largest I could find. I ask the drugest if it had any additives because I was going to burn it in my model airplane engine. His reply was that it was that it was USP so it was pure and then we got into a half hour discussion about model airplanes and such. I poured an ounce or so into the fuel and shook it up well. No noticable extra smoke, and the engine seemed to run fine. I think I'm going to put another ounce in what is remaining fuel and do my last two break in tanks and first flight using it.

I need to find a source of castor oil locally, the stuff at the drug store is expensive. Around $1.20 an ounce.

Hope the wind is calm in the morning, I may get to test flight my plane.

Don