RE: .12 Rigger Kits for CHEAP!
The higher % of castor oil in the 33% would be better for break in, but I don't know that engine and what mods are done to it, and how it will react to even lower % of nitro. It definitely won't perform any better but IMO it will be better for break in. From the reading I have done and engines I have delt with, the Higher Quality an engine is the harder it is to break in, and the importance of doing it right. Most Mod engines are using 40% nitro "Minimum". Dropping down nitro% will only drop performance a little, when you go back to 40% just run 1 easy tank through it before you hammer down.