I have a bit of surface rust starting on the lower corner of my passenger-side door. I have been looking at ways to fix this and I know that I need to remove all the rust so it won't come back. My question is this: which is better, the rust dissolving gel or the stuff that chemically converts the rust into a paintable primer? From what I can see both have their advantages and disadvantages, but I wanted to see what some more experienced people had to say first. Thanks.