If you hate rust, try this stuff!
 

Did anyone ever try this Loctite Extend stuff? About a year ago I found some real rust problems under and around the battery, also in the well area in front of the spare. I freaked! I ran down to Home Depot grabbed a bottle of Loctite Extend liquid. I took it home, removed as much rust as I could, wire brushed the area, and brushed this stuff on 3 coats wet on wet. It dries to a dark color, almost looks plastic coated.
A year later, I removed the battery and the area is clean, no rust anywhere!
I really dont know how well it takes paint, but if you have to stop rust somewhere other than body panels, this stuff works.
I know It sounds like a dopey commercial, but I dont work for them. I just hate rust more than most folks.
JoeF

Rust never sleeps, no matter what you put on it.

Stephan

I've tried it - it sucked for my application. I recommend POR-15 instead.

Try phosphoric acid. It's been a few years sonce chemistry 101, but the acid changes rust ( feric/-ous?? oxide) to iron phosphate. I'm sure the chemistry gurus can be more exact. Comercially it is sold as Rust cure, Aspho and others at hardware stores. You can paint over the dry surface. Good luck.

AKA "Metal Prep." It's the last step before you begin coatings. No matter how clean and shiny you think the metal is, if you don't use the acid stuff then you may wind up with rust under the coatings.