Rust, blueing, browning. All are oxidation.
Rustoleum, in the brush on, has a fish oil additive. That penetrates the oxide points and prevents additional oxygen entry.
Oil floats on water.
Using oil over an oxidation point accelerates oxygen entry.
Oxpho contains rusting. It is a creamy liquid that has a phosphorus base. Phosphoric acid. It is similiar to Naval Jelly except it hardens and can be sanded.
None of these methods are a permanent solution.
When I do touch ups, I spray Easy Off oven cleaner on the "wound". This eats everything. I hose off and scrub with light dish soap and a 3M plastic sanding pad.
I then use Oxpho. After it hardens, I spray Krylon, which is acrylic. This makes an encapsulation and furthers the hardening of the Oxpho. It is like waxing over laminating resin to complete the cure.
After a few days, I sand the Oxhpo, Krylon, down to metal. I reapply Oxpho. I add Bondo where neccessary, apply fine filler, sand, and brush on Rustoleum.
It works better than than a bandaid. It is not the permanent solution, but it works longer than most other methods I have tried.
Rustmort is another alternative, if you can find it.