White vinegar takes the oxidation off the aluminum (also kills bacteria that cause bad odor). I mix it with water (1:1), and use "brillo" pad soaked into the solution to take MOST of the oxidation off. This cuts the polishing time in half (or better). 1200 wet sandpaper takes all scratches out (for deeper scratches, if any,you need coarser sandpaper, to start with, followed by gradually finer one). The more grades you skip in the process, the more time you will spend on rubbing the scratches off.
Did you ever end up with hard water stains on your car (from sprinklers)? And did you end up paying X amount of Dollars to have them removed in the car wash? If you catch them on time, you can take them off with soft sponge soaked in white vinegar. This IS what is used in car wash industry for that. Vinegar will strip the wax as well, and the car needs to be rewaxed. If the water spots are "baked in" by the sun (for several days), you will need to soften them up with white vinegar, followed by the "clay bar", and then polish and wax (gets to be labor intensive/expensive procedure in the car washing business). IF the water spots are left untreated, they WILL "eat" into the clear coat, and it will start flaking (time for the new paint job). You can either do this yourself, or pay the pros to do it. Either way it will cost you time and/or money.
I also use it to remove hard water deposits/sediments from sinks, bathtubs, etc (instead of "CLR" type of chemicals). It works, it's harmless (for pets AND humans), and I use it regularly on dog's/horses water thoroughs and such.
I owned two gas stations, with full service car wash/detail until recently (sold the last one in 2011). There are other "acids" used daily in car wash industry, to wash/prep aluminum wheels, and some of them damage the rims ("burn") pretty bad. I used vinegar for that purpose for over ten years, with excellent results, and no damage claims. Try it next time you get an oxidized Kirby, you can thank me later! LOL