I think Ospho is way too much trouble for normal rust. Too toxic to work with face up, under truck. It must be neutralized properly or paint will fail. It's feeakin ACID.
Rustoleum Reformer does the trick, no rewash, no residue. Paintable within a short time.
There are other brands of reformers, encapsulators for normal rust. Not too flaky of rust. See instructions on can. They are very good. No fuss.
Converters (ospho) need 100% rust. It's for those who have very pitted/bad rusted/flaky sheet metal. Some people like the smell of Phosphoric Acid.
