da Rock

If you're flying 4cycles, they often run better on slightly higher nitro. The heat keeps the glowplug glowing between firing strokes.

If you're flying small 2cycles, higher nitro is good because they don't usually have enough mass to keep themselves hot enough.

Any major brand of fuel is going to be good. And did I mention that there aren't any magic fuels?

Very often, an engine that isn't running too good will run better if you switch fuel. This usually leads the flyer to decide that he has discovered THE MAGIC FUEL and he then feels compelled to spread the word for the rest of his career. What has usually happened is that his engine had the wrong heat range glowplug for the fuel it was acting up on, and the new fuel matched the heat range of the plug. Or sometimes changing the nitro content will match the timing in the engine better than the old nitro percentage did. The amount of nitro affects the timing of the engine. Change the nitro content and the fuel fires off earlier or later. Change the fuel and sometimes the change in timing gives better performance just from the change in timing. And sometimes the engine is lugging the wrong size prop and a different fuel (nitro/timing/oil content/operating temperature) matches up with that prop. Or sometimes the prop is too small to keep the engine loaded, the engine runs too cool and winds up running lousy, and a hotter running fuel solves the problem. Magic? Not really.