Originally Posted by NIGHTMAREWS.6

Depends on the how the piece is your polishing, if there's alot of pitting, i would use something in the 300 range, and up from there, to get it really smooth you will need to use a fine grit in the 1500-2000, once its totally smooth, then start buffing. The rotation of the buffing wheel at 3600rmp or more will heat up the compound, and thats where the magic happens. I'll see if i can dig up some before and after shots, i sanded off every piece of rust i could find under my car, especially the axles, and used por15 in a black gloss, and no more rust since then. replaced all my suspension, polished everything else. Not hard to do, just time consuming.