We have always been impressed with the Captain Phab line of cleaners (the Purple Power Cleaner and Black Streak Remover both tested very well in our onboard trial last year). They have a new cleaner designed just for aluminum, which so easily oxidizes and turns grey and powdery in our environments. The new acid-free Aluminum Magic and its partner Aluminum Brighter gel are just what boaters need to keep those aluminum bits looking clean and ship-shape. $20 for a 22-oz sprayer.
Check out the rest of their extensive line of quality cleaners at www.captphab.com.