Before breaking it in with nitro, i prefer a pre break in. a break in before the break in. First i remove the plug heat it with a hair dryer, pour oil in the plug hole, cover the hole with foam. start it with a tarter box for a long until it gets a little lose, if you think it's time to use nitro for the real break in, heat it again with the hair dryer. you will notice the pinch will be less and then can be started with the starterbox. (the gradual you break the engine in the better! and the longer it will last. specially if you the time to replace the air filter replace it with a clean one. i always have spare air filters ( i frequently replace them when it's time to). i have two other spare airfilters always with me. This is how i take care of my Cobra.