Nope, I used the Optimum Metal Polish as well and the little bit of black that comes back between washes just wipes off.

Yes, after polishing it, just make it a habit to wipe them clean everytime you wash your car (just a damp rag will do) to avoid getting a hard build-up again.

Thanks. I'll try next time I wash the car.

Use this...
http://eagleone.com/pages/products/p...sp?itemid=1006

If it is really bad, use this...
http://www.autozone.com/autozone/acc...ntifier=142419

Those IMO are the best polishes you can buy.