Found a mint 1977 puch moped with 150 miles on it. Got it running after a quick tank/carb clean, then ceased up the engine after rust and varnish from the tank worked its way down in to the jug. Got that free again, cleaned the tank with acid, flushed it with a garden hose and thought I had it. Then the tank flash rusted again. Thinking about using Kreem to coat the tank, but worried about how it will apply. Seems to be made for tanks that can be removed ANy advice on how this stuff works?