# Removing aluminum “corrosion?”

I have some aluminum alloy, possibly 6063 or 7050 (no clue really) which has corroded. The finish might be silver-anodized but I doubt it due to the high polish, could be urethane. The item is a fishing rod holder, used in a freshwater marine environment. Hardware is stainless and steel. Several screws and bolts need to be removed, and I was wondering if there was an acceptable reducing agent for the corrosion rather than busting driver bits and/or mangling threads.

Aluminum corrosion in most environment produces $\ce{Al2O3}$, corundum, which is extremely hard (9 on the Mohs scale, where 10 is diamond). Corundum is also quite resistant to most chemicals.
There are various products called "Aluminum Jelly", such as that from Loctite and from Henkel, which can remove some of the surface corrosion. They probably attack the aluminum at its point of contact with the oxide, rather than reacting with $\ce{Al2O3}$ itself. Regrettably, this probably means that though it might brighten the surface, the jelly will not substantially free the bolts.