According to veteran bodyman, painter, and hot rodder Carl Brunson, Rust Bullet is the best thing he’s ever seen for use over, and prevention of, rust.  
Rust Bullet is a two-application product that penetrates the porous rust and reaches the metal underneath, producing chemical activity. Basically, the rust becomes intertwined in the resin matrix of Rust Bullet and remains a permanent part of the coating. The second coat of Rust Bullet fills any pinholes in the first coat and forms a nearly impenetrable coating that protects the metal.
  
Silver gray in color, Carl points out that while topcoats aren’t required, conventional paint can be applied over the second coat for appearance. Rust Bullet offers excellent abrasion resistance and is quite difficult to scratch (which makes it excellent for suspension components). If a scratch or chip in the coating does occur, the metal will rust in the breached area, but rust will not proceed beyond the breach. Rust Bullet will not lift, blister, or peel away from its leading edge in any significant degree. Simply reapplying Rust Bullet over the scratch or chip reseals the coating, proving easy, low-cost maintenance.