You get a fine mist of spit back out the carbs also. One thing that helps a lot though is to make sure all the exhaust unions are not leaking. If necessary use a dab of high temp RTV (red silicone) on the 2 stroke muffler flanges and use teflon tape on the 4 stroke muffler threads. Don't overlook the ends of the long bolt that holds mufflers together and the center joint in mufflers as well. When you get home take a toothbrush with a little acetone on it and go over the engine and muffler after each day of flying. This helps a lot to keep the build up from getting out of hand. I quit using windex on the engine because over time it grays the aluminum I think. Personally I hate cowlings because it makes it hard to do these things.

Ernie Misner