Cleaning shower door frame

[Barb]

The aluminum frames of my shower doors are starting to change from a shiny finish to a dull and dirty looking finish. I clean them with my regular shower cleaner, but they always look dirty almost to the point that the finish has changed color. Any suggestions what I could use?

[Vox Humana]

I have had good results with a product called "Met-ALL"

[Phisherman]