Why not try the waxoyl?

Rust mort is good to change the properties of rusted metal. Napa has it. I have brushed it on lightly and heavily rusted areas with good success. Ugly but it stops rust for the time being,
Another home brew rust killer is phosphouric acid.. buy the strongest chrome wheel cleaner loaded with Posphouric and watch light rust disappear. Works to stop rust until treatment or repair. They are short term solutions.
Prevention is the cure... I say waxoyl