With most RC fuels you should run out the fuel in your motor when finished for the day. The fuel is hydroscopic; attracts moisture from the air, therefore causing rust in your motor. As an added measure after run oil needs to be used. Clean out the area around the glow plug, remove it (make sure absolutely no dirt enters the engine) and put 3 or 4 drops of this oil in. Spin the motor on your starter box for several seconds to ensure is spread out inside the engine. If you follow this procedure you will ensure that no rust forms in your engine and prolong its life.