[john hall]

Never had a problem using Seafoam dumped in the gas tank. I don't measure, just make an educated guess as to how much fuel is in the tank and how much Seafoam I am pouring in. Never had it to cause a problem. Of course I've never tried using it in anything that was really gunked up, just stuff that was running a little rough. As long as you don't expect it to perform miracles I think it works great. If your fuel tank is full of water and trash or you carb is completely gummed up, you're going to have to turn some wrenches.