you'll find that Barkeeper's and Zud are both cleansers that list oxalic acid as active ingredient...that's why (combined with abrasives) they remove rust and corrosion on many metals. Barkeeper's is usually available (at a much lower price than Billy Sonoma's) in hardware stores and such, cheaper than Zud, too. I follow up the cleanser treatment with a polish like Simichrome and then automotive wax.