GMC 1999 Sierra 1500 Pickup Owner's Manual page 368

Service & Appearance Care
Finish Damage
Any stone chips, fractures or deep scratches in the finish should be repaired
right away. Bare metal will corrode quickly and may develop into a major
repair expense.
Minor chips and scratches can be repaired with touch-up materials available
from your dealer or other service outlets. Larger areas of finish damage can
be corrected in your dealer's body and paint shop.
Underbody Maintenance
Chemicals used for ice and snow removal and dust control can collect on the
underbody. If these are not 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 areas where mud and other debris can collect. Dirt packed
in closed areas of the frame should be loosened before being flushed. Your
dealer or an underbody washing system can do this for you.
Chemical Paint Spotting
Some weather and atmospheric conditions can create a chemical fallout.
Airborne pollutants fall upon and attack painted surfaces on your vehicle. This
damage can take two forms: blotchy, ringiet-shaped discolorations, and small
irregular dark spots etched into the paint surface.
Although no defect in the paint job causes this, General Motors 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. This applies only to materials manufactured and sold
by General Motors. Bodies, body conversions or equipment not made or sold
by General Motors are not covered.
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