I used a product from Swish a long time ago that was used for brightening up aluminum and it worked extremely well. If you've seen the part of an R bike where the flywheel and clutch are, you know how dirty and corroded the surface of the aluminum can be in there.
This is after I used that product. All I did was brush it on and rinse.
Aluminum that is protected from the elements by anodizing will look good for a long time. The problem is products being used by owners that is either abrasive or acidic.