I'm an automotive enthusiast myself, and I can vouch for fluid-film. It kept my SAAB 9000 from getting any rustier during two road-salt-saturated Vermont winters. I never applied it to a car myself though, because it requires spraying equipment and a shop to collect all the drips. It also comes in a spray can with a tube so you can get it down inside the frame pretty well, but you'd need a lot of these to do a whole car. But inside a bike, you'd need probably less than a single can, so it'd be fine. Actually I might buy a spray can for my Claud Butler now that I think about it...