If you have a 2.5 DO NOT GET ANYTHING BUT THE TRAXXAS FUEL! The makers of the engine and the fuel spent years and research on these 2 things. They highly suggest for great proformance and engine life to use traxxas top fuel with the 2.5 engine. Also, watch the break in video, it will tell you a certain way to break in the engine.

I bought the 2.5R engine for my nitro 4-tec, watched the break in DVD, and broke it in. I have no over heating problems and nothing has gone wrong with the engine.