After you remove the rust scales from the metal on your car, you need to apply self etching primer. ... It's purely a surface coating, and it doesn't stop the rust. It does, however, prevent the rust problem from worsening.

Can self etching primer be used on rust?

Using Self Etching Primer

You should only use a single coat of it as it is meant as a cover for rust more than anything else. Unlike other primers, you can't use self etching primer then keep the car outside until you're ready to paint it.

Does rustoleum self etching primer stop rust?

Rust-Oleum® Self Etching Primer prepares bare metal, aluminum and fiberglass surfaces to promote maximum adhesion and smoothness of the top coat. This product is formulated to stop rust and is an essential step to achieve a professionally finished look.