I have to say, and not to put Gords Polish in less light, but...
The oxidation on aluminum is easily taken care of by Acids. Thats all thats involved in the science of metal.
We sell a product that for guys with rigs just pray on, hose off and the aluminum looks like it was just polished.
Whats the secret? Ethylene glycol, Phosphoric acid and Ammonuim Bifuoride, and water, nothing else. it eats
away at the oxidation and leaves the shinny metal behind.
The best part is, your not working your ass off. Now to get it to a high mirror, polish it, but clear coat will not
stick well to smooth surfaces so....
you can either: 1) polish all the time,
2) use chemicals,
3) or etch and clearcoat.
heres a link for one of the acid based products out there, just click on the aluminum trailer cleaners, theres a few to choose from.
http://www.lyndist.com/acidcleaners.htmlnot for everyone, but it might make someones life easier

Rebel