If its raw cast aluminum like blocks etc, and you want to bring it back, or its raw stock like sheet or tube with natural grain, you can use a product called "Toon Brite".
Its a mild acid, for cleaning aircraft and boat pontoons. It works great on aluminum casting and sheet. Doesnt affect the material, but it clouds a tiny bit on cnc machined forged aluminum or polish.
But if you are on those surfaces, its awesome. You just wash it off after 5 minutes.