I've been using morgan fuels coolpower full synthetic GREEN 10% nitro.I use it all the time, break-ins,4 strokes, and 2 strokes. I have Never had a problem with heat, rough running engines,or brown junk baking to the outside of the engine/mufflers. I recommend this fuel to everyone I talk to. It helps my engines run cool,clean, and I think it smells better when burning.