Fuel Tank Sealer coats the inside of your tank to stop rust and seal pinholes and weld seams. It’s a non-porous, flexible film that is resistant to all fuels, alcohols and fuel additives. This environmentally safe sealer does not contain the harmful chemical Methyl Ethyl Ketone (MEK) and is non-flammable. Cleaner Degreaser and Metal-Prep must be used to prep fuel tank prior to using fuel tank sealer.