Nitromethane by itself is very acidic.However, It makes its own Oxygen when ignited.Oxygen will destroy almost any kind of metal,except for your precious metals,(gold,platinum,silver, chrome,aluminum,(which is't precious) you get what I mean. Anyway, Why would you want to run any engine lean except for: Dragsters,Pylon raceing, and combat. You will only get 2-3 runs out of any engine if you lean out your engine to the max. Otherwise,go easy on your motor. Unless you have unlimited funds! Ha.