Had some good results with KrudKutter. The one that says "a must for rust",prediluted in the spray bottle does have phosphoric acid in it but also the grease/dirt cutting agents. The "Original" KrudKutter doesn't have the phosphoric acid in it.
You can also buy Krudkutter "must for rust" on its own, that's phosphoric acid but no degreaser/cleaners and I haven't tried it yet. I was thinking of mixing it with the "Original" to approximate the other one but understand that any phosphoric acids at higher concentrations may stain/blacken the aluminium in some blotchy way you may not like.
Impossible to find in Canada anyway all of them KrudKutter products.
Lets see what you have to deal with, I might just tell you to buy Rub'n'Buff Silver Leaf, the cheap and very easy way to apply a wax/pigment coating to even out aluminium. Works well and as it is a wax product will prevent further oxidations.
Have tools, will travel!