Agreed ^ There are two versions of Autosol too - a coarse version in a tube, and a fine version in a tin. I use a mini polishing pad designed for headlights in my battery drill. One pad for the coarse to take the discolouration out, and then another pad with the fine to make it shiny. It does take a long time and its never quite perfect but its better than nothing. Mask off the paintwork beforehand if you're using that method though!
Wrapping it satin black is better still