Has anyone tried seafoam? I've used it a few times but I'm not sure of a few things. First, does it smoke everytime you do it or is the smoke supposedly the gunk being cleaned out? I'm confused as whether the smoke is from the cleaning or just the engine burning it since it is a foreign substance. Also, is it bad to use seafoam a few times in a row? If the smoke coming out means the engine is dirty and being cleaned, I would like to do it multiple times the same day to make sure it gets it all out.