How to clean galvanized steel?

Q. My friends and I recently acquired a restaurant. The previous owners used Galvanized Steel siding for the walls on the inside of the restaurant. It looks nice but is a real pain to clean especially in the bathrooms. I am no expert in metal so if you can help me please put it in simple terms. But my question is how do I get them clean? It looks like there may be a build up of hard water and some other cleaning solutions especially next to toilets. We have tried several cleaners some will get the spots off but leave behind a film that takes away the shine of the metal. Once we get them clean what do we put on the walls so that we can keep the nice look of the metal but be able to wipe them down?

A. DEAR SIR

THE WHITE STUFF WHICH LOOKS LIKE DIRT MAY BE ZINC OXIDE. CLEANING WITH ACID OR ALKALI MAY DISSOLVE YOUR ZINC, I WOULD ADVISE USING pumice ⇦ on eBay or Amazon [affil link] OR OTHER SOFT ABRASIVE, AND TO PAINT CORRODED AREAS. OTHERWISE YOU'LL HAVE CORROSION OF THE STEEL VERY FAST.

GOOD LUCK

Khair Shishani
aircraft maintenance - Al Ain, UAE
2004