Just bought and using "speedy all metal polish" on a set of american slots. Bought on-line as I could not find it near me. I first found it at a truck stop. I believe it's made from buffing compound in a solvent based wax. I used it with 4-0 steel wool, and then buffing with nubs.
Pretty easy to use and I like that it's a solvent based product. I'd be careful using wax on valve covers due to heat issues.
There is a product I've seen, but have not tried called opti metal coat that a local paint shop has literature on, but no reports of buyers. Seems it's like a chemical clear coat that bonds to the metal and is great for non-cleared (open) aluminum.