I use a product called "Purple" from California Custom. I have used Autosol, Mothers and Turtle Wax metal polishes over the years, however like the Purple best for ease of use and shine. You may be able to find it locally. In my area some auto parts places have it, as well as some of the heavy truck dealers as they sell it for doing aluminum tanks, wheels etc.
Company site;
http://www.californiacustom.com/purple_metal_polish.htmlAmazon has it also;
http://www.amazon.com/California-Custom-...s=purple+polish 
