Cadillac 2007 CTS, Owner'S Manual, Page: 443 / 518

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 or
an underbody car 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 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, GM
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.
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