1993 Buick Skylark Owner's Manual - Page 256

Underbody Maintenance Chemicals usedfor ice and snow removal and dust control can collect on underbody. If theseare not the removed, accelerated corrosion (rust) can occur the on underbody parts suchas fuel lines, frame, floor pan, and exhaust system even though they have corrosion protection. x Chemical Paint Spotting Some weather and atmospheric conditions can create a chemical fallout. Airborne pollutants can upon and fall attack painted surfaceson your vehicle. This damage can take two forms: blotchy, ringlet-shaped discolorations, and small irregular dark spots etched in the paint surface. Although no defectin the paint job causes this, Buick will repair, at no charge to the owner, surfaces of the new vehicles damaged by this fallout condition within 12 months or 12,000 miles (20 000 km) of purchase, whichever comes first. At least every spring, flush these materials from the underbody with plain water. Clean areas where mud any and other debris can 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. 255