[MazdaMike]

Some people are all like ahhhh "Cut the rust out." Or someone else will say "Sandblast it, then refinish." Or Someone else will say "Bomb the rust with a convertor, and refinish."

Its usually just answers based on personal opinion and experience.
Personally if its just surface rust, I'd just sandblast it, grind it and refinish with bondo. If its more extensive just cut out and replace the area. Those are the sure fire ways of defeating rust. Now If you just grind it and refinish it will surely come back and I've seen it many times.