Let's be clear - is it Chrome (like your thread title says), stainless steel, or aluminum?
Each need a different product and process to clean and polish effectively. For example, use a chrome polish on stainless and you may damage it permanently.
Is it rusting, corroded, dull, stained, or scratched?
There are a zillion metal polishes out there. Some are targeted to specific markets, like truckers or food services. There are polishing kits used with a drill or bench grinder that can completely restore the piece if used properly. Lots of options out there; maybe too many.
I'm hesitant to offer metal polishing advice because if it goes wrong, it cannot be undone easily. Screw up paint polishing and its usually no big deal to fix. Screw up metal polishing and you'll need a pro metal polisher to fix it, or you'll have to replace the piece.
