Chevrolet 2011 Express 1500 Cargo Owner's Manual page 366

If dirt and/or contaminants build up
in the glass seals, use a cloth and
water to clean the glass seals.
Silicone grease on weatherstrips will
make them last longer, seal better,
and not stick or squeak. Apply
silicone grease with a clean cloth.
During very cold, damp weather
frequent application may be
required. See
The best way to preserve the finish
is to keep it clean by washing it
often.
.
Do not wash the vehicle in direct
sunlight. Use a car washing soap.
Do not use cleaning agents that are
petroleum based or that contain
acid or abrasives, as they can
damage the paint, metal or plastic
on the vehicle. Approved cleaning
products can be obtained from your
dealer. Follow all manufacturers'
directions regarding correct
product usage, necessary safety
precautions and appropriate
disposal of any vehicle care
product.
Rinse the vehicle well, before
washing and after to remove all
cleaning agents completely. If they
are allowed to dry on the surface,
they could stain.
Dry the finish with a soft, clean
chamois or an all-cotton towel to
avoid surface scratches and
water spotting.
High pressure car washes may
cause water to enter the vehicle.
Avoid using high pressure washes
closer than 30 cm (12 in) to the
surface of the vehicle. Use of
power washers exceeding
8 274 kPa (1,200 psi) can result
in damage or removal of paint
and decals.