Mixed up gas and ATF yesterday and ran two gallons through the Cub between idling ad various speeds and driving it around. The engine did seem to run a bit smoother and some power returned but I am still getting some popping through the air cleaner when I idle up, or down. I did get some white smoke coming out of the exhaust and black spots out the exhaust as well on the hood. I plan to put ATF in the spark plug holes next and try that and see where that gets me. Might be a stupid question, but after putting ATF in the spark plug holes is an oil change needed before running the engine?