The problem being that once a protective layer has been breached and rust has started you can "clean" it but if you don't protect the metal it will rust again. Keeping the gas tank as full as you can will not stop rust. As you use gas it pulls moisture laden air into the tank.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.