RE: What kind of fuel to use?
I've been flying Sig Champion 10% Nitro, 20% oil, half castor, half synthetic, for many years. I run it in TD 09, McCoy Red head 19, Fox stunt 35, K&B 4011, and Tower 40. A mix of iron and steel, ringed, and ABC engines. It works fine. I am presently flying fuel that is four years old.