GMC 2011 Sierra Denali Owner's Manual page 440

10-96 Vehicle Care
Tires
To clean the tires, use a stiff brush
with tire cleaner.
Notice: Using petroleum-based
tire dressing products on the
vehicle may damage the paint
finish and/or tires. When applying
a tire dressing, always wipe off
any overspray from all painted
surfaces on the vehicle.
Sheet Metal Damage
If the vehicle is damaged and
requires sheet metal repair or
replacement, make sure the body
repair shop applies anti-corrosion
material to parts repaired or
replaced to restore corrosion
protection.
Original manufacturer replacement
parts will provide the corrosion
protection while maintaining the
vehicle warranty.
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 major repair expense.
Minor chips and scratches can be
repaired with touch-up materials
available from your dealer. Larger
areas of finish damage can be
corrected in your dealer's/retailer's
body and paint shop.
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.
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.