RE: COX .049 plane engine Fuel
Cox instruction sheets say to run the engine for ONE MINUTE rich annd then lean it out. 15% nitro is a little on the low side. Cox sport fuel (blue can) is 25% nitro and the racing fuel (red can) is 35% nitro. The little engines lose their heat very quickly and the high nitro keeps them hot. They run 100% better on high nitro fuel. 20% oil is perfectly fine. Itis the oil content of Cox fuels and it's all castor.