Quicksilver is an acid-based wheel cleaner that can damage the clear coat finish on many BMW wheels. Most popular wheel cleaners on the market are either acidic or highly basic. There are two German wheel cleaners available that are close to pH neutral: P21S is the least aggressive of the two and works well on wheels that don't have lots of brake dust. Sonax cleans almost as well as Quicksilver, yet will not usually damage the finish.
Another trick to maintaining wheels is to clean them thoroughly and apply a coat of wax. The wax helps protect the wheels from hot brake dust (which turns acid when wet) and allows easier cleaning. Sonax also make a nifty product called Hard Wax Spray. This is an aerosol hard wax that sprays on the wheel and requires little buffing. It provides an excellent protective coat with very little effort.
Author: Larry Reynolds
Car Care Specialties, Inc.
Reprinted from the Kansas City BMW Club newsletter - Milepost, Nov/Dec 1996