Before I fire up my new OS .91, I need to add some more oil to my fuel. I have a new gallon of Powermaster 10% that contains 18% oil. Anyone know how much caster to add to up it to 23% oil content. It's been too long to try and remember how to do the math. I am assuming that everyone is using at least 23% oil per the OS instructions. I suppose I will break it in per the instructions with a 12x6 wooden prob cut down to 10". Sounds like a recipe for disaster to me spinning a hacked on wooden prop at 20K. What are you guys doing for break in?

Thanks,

Mark