Saturn 2009 ASTRA - Manual (Page 264)

Underbody Maintenance
Chemicals used for ice and
snow removal and dust control can
collect on the underbody. If these
are not removed, corrosion and rust
can develop 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 debris can collect.
Dirt packed in close areas of
the frame should be loosened before
being flushed. Your dealer/retailer
or an underbody car washing
system can do this.
Chemical Paint Spotting
Some weather and atmospheric
conditions can create a chemical
fallout. Airborne pollutants can
fall upon and attack painted surfaces
on the vehicle. This damage can
take two forms: blotchy, ring-shaped
discolorations, and small, irregular
dark spots etched into the paint
surface.
Although no defect in the paint job
causes this, we 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 occurs first.
9-80 Vehicle Service and Care