Gas tank sealers are sold by quite a few places including lot of the radiator shops that clean gas tanks. I just took mine in and it soaked for a couple of weeks to get all the rust and other crud out of it. A red sealer was put in after that. Seems to work great. The radiator shop people said the sealer usually lasts eight to ten years. Mine was not leaking but I could see rust forming in the tank and wanted to take care of it as soon as possible. I thought the $100 charge for what they did was a very reasonable price.