If I've already asked this question on this forum then I apologize. I searched my past posts but didn't see it.
I have an aluminum horse trailer that has started to oxidize. The aluminum used to be nice and shiny but now it's a dull grey. We could hand polish it but that's a ton of elbow grease and I am lazy by nature. I've been told that an acid wash I the best option but I've also been told that it can damage the white fiberglass panels that make up the upper sections of the trailer. Our pressure washer takes the grime off but does nothing to brighten the aluminum. In there anything I can spray on the aluminum and then rinse off. I know I'm looking for the easy way out and there probably isn't one, but I'm hoping the hive has some suggestions.
Zep-A-Lume.
Park the trailer over somebody else's lawn, spray this stuff on, wait five minutes and hose it off. It will be shining like the diamond plate on the firetrucks in a parade.

Keep in mind that anything you do will likely remove the anodized finish and you'll be chasing oxidation monthly.
Anodizing puts a layer of hard, oxidized aluminum on the surface. One it is compromised, you're left with unprotected aluminum. Think of it like a varnished piece of wood. Once you notice the varnish is compromised, you sand it pretty again, but without the varnish on it, it will weather quickly. In the case of wood its easy to put more varnish on. Aluminum isn't easy to re-protect.
We've talked about polished aluminum aircraft for years. It always cam pack to the monthly buffing. Then someone had the idea to contact AirStream to see if they'd sell the cleat coat they put on their trailers. Can you clear aluminum?
Thanks for everyone's input. I'm going to pick up some Zep-A-Lum. If it dulls back down in a month that's OK. We're not showing the trailer just the horses. I should've known that a fire fighter would know how to make shiny stuff shinier.