Hi Keith. I put in a brand new OS 8 glow plug, and double checked to see that it was burning brightly on the glow igniter. I'm using 20% Trinity Monster fuel. It was running fine on it for about a month. I forgot to ask the previous owner what fuel he was using though. The flywheel is hard to turnover with and without the plug in. It seems to stick at almost TDC. The motor is a stock Nitro Star T-15 with roto start.