What to protect large panels of aluminum with?

[bigirn]

I have a fairly new horse trailer with lots of what I believe is unprotected aluminum on it. What would you folks use to keep it from oxidizing and dulling over time? Keep in mind there is a lot of it, roof, fenders and the like.

Thanks for your help, it's much appreciated!

[Rsurfer]

Opti Coat..20cc will do two cars.