I have started to take off my baggage doors (not basement type) so I can do a proper paint job on the bottom of our 1990 Champion Lasallle motorhome. The bottom sides are galvanized metal except where...
Vinegar is great in cleaning oxided galvanize metals, it will help in prolonging the paint applied, yes longer than when no vinegar at all. It was used back in its time as a wash to remove the oil residue that was on the surfaces Nowadays there are special primers available that would do better