https://www.kbs-coatings.com/tank-sealers.html You can thank me later. KBS has a complete kit for motorcycle tanks - stripper, prep, sealant. I have used it on fiberglass with success. Fiberglass is well known for being a PIA to seal reliably for a motorcycle tank. You will need some small nuts/bolts to use to break the rust up when using the stripper. Follow the directions to the letter.