I recently picked up a set of late 70's BMW 3-series Alpina rims.
All looked great except for one. What I thought was a mismatching gunmetal finish was actually baked-on brake dust and road grime.
I tried using a foam drill polishing attachment with metal polish creme. It took me 30 minutes to barely clean one spoke. I've got many more to do.
I then bought Palmolive Oxy Power, mixed it with Oxy Clean granules, and slathered this mixture all over the wheel. I waited about 30 minutes, and then went at it with a Brillo pad.
This seemed to take out at least a layer of this baked on grime, but not all of it. Does anyone else have suggestions for cleaning? I'd love to use BBQ cleaner, but I really don't want it to eat up the aluminum.