1997 Buick Riviera Owner's Manual - Page 295

Underbody -Maintenance Chemicals usedfor ice and snow removal and dust If control can collect on the underbody.these are not removed, accelerated corrosion (rust) can occur on the underbody parts such as lines, frame, floor fuel pan and exhaust system even though they have .corrosion protection. Chemical 'Paint Spotting Some weather and atmospheric conditions can create a chemical fallout. Airborne pollutants can fall upon and This attack painted surfaces on your vehicle. damage can take two forms: blotchy, ringlet-shaped discolorations, and small irregular dark spots etched into the paint surface. Although no defect in paint job causes this, Buick the the At least every spring, flush these materials from of underbody with plain water. Clean any areas where mud will repair, at no charge to the owner, the surfaces new vehicles damaged by this fallout condition within Dt i and other debris can collect.r packed in closed areas 12 months or 12,000miles (20 000 km) of purchase, of the frame should be loosened before being flushed. whichever occurs first. Your dealer or an underbody car washing system can do this for you. 6-58