The best paint imo for rust and making non body panel surfaces cleaned up is Chassis Saver. Instead of driving around town for it, I tried rust oleum rust and reform. It seems decent but I later switch to regular ole black rust oleum oil based paint. For the price, the oil based product doesn’t seem much worse than chassis saver.
I used a wire wheel brush attached to a drill and grinder to clean this up. Wiped with lacquer thinner and brushed on 2 coats under this passenger fender
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