1993 Buick Park Avenue Owner's Manual - Page 286

Underbody Maintenance Chemicals used for iceand snow removal and dust control can collect on the underbody. If these arenot removed, accelerated corrosion (rust)can occur on the underbody parts such as fuel lines, frame, floor pan, and exhaust system even though they have corrosion protection. At least every spring, flush these materials from the underbody with plain water. Clean any areaswhere mud and other debriscan collect. Dirt packed in closed areas of the frame should be loosened before being flushed. Your dealer or an underbody vehicle washing system can do this for you. Chemical Paint Spotting Some weather and atmospheric conditions can create a chemical fallout. Airborne pollutants can fall upon and attack painted surfaces on your vehicle. This damage can take two forms: blotchy, ringlet-shaped discolorations, and small irregular dark spots etchgd into the paint surface. Although no defect in the paint job causes this,Buick will repair, at no charge to the owner, the surfaces of new vehicles damaged by this fallout condition within 12 months or 12,000 miles (20 000 km) of purchase, whichever comes first.