I recently checked my penthouse bolts and found some were rusting. Using a wire brush and the wire brush attachment on my Dremel, I removed the rust.
Then, I coated all the bolts, nuts and washers with Permatex Rust Treatment. After that dried, I painted them with an oil based Rustoleum primer. After that dried, I painted them, again, with an oil based Rustoleum paint. I'm happy with the results and hope they last.