“I used a sealer on my steel Fire extinguisher tank that worked wonderfully. — http://www.kbs-coatings.com/Tank-Sealers_c_7-1-0.html”
See entire thread HERE.
"Finished my fuel tank this past weekend and all went well. I had first started with cleaning the tank and welding a few holes up in my 44 gallon aluminum tank. I do have to say that this all took a matter of weeks to complete because of proper drying and work schedule. The process was very straight forward. I couldn’t believe how well the Gold Standard coated the inside of the tank with multiple baffles in the tank. I then painted the exterior with gloss black. This being in the hull of my boat never to be seen by sun again but it sure looks good. Thanks for such a great product!"
Patching Larger Holes on Your Gas Tank