Some years ago a mate of mine bought a new metal petrol tank for his Royal Enfield motor bike,bare metal from India. When it arrived it needed a couple of modifications to it and once this was all done there was a bit of rust forming over most of the surface. He then wanted me to clear coat over it to keep the look. Every time I see his bike I wish I had not done that because to me it just looks a bit neglected, but he likes it and I guess that is all that matters.