GMC 2012 Savana Owner's Manual page 341

Regularly clean bright metal parts
with water or chrome polish on
chrome or stainless steel trim,
if necessary.
For aluminum, never use auto
or chrome polish, steam, or
caustic soap to clean. A coating
of wax, rubbed to high polish, is
recommended for all bright metal
parts.
Use only lukewarm or cold water, a
soft cloth, and a car washing soap
to clean exterior lamps and lenses.
Follow instructions under "Washing
the Vehicle" later in this section.
Clean the outside of the windshield
with glass cleaner.
Clean rubber blades using lint-free
cloth or paper towel soaked with
windshield washer fluid or a mild
detergent. Wash the windshield
thoroughly when cleaning the
blades. Bugs, road grime, sap, and
a buildup of vehicle wash/wax
treatments may cause wiper
streaking.
Replace the wiper blades if they
are worn or damaged. Damage
can be caused by extreme dusty
conditions, sand, salt, heat, sun,
snow and ice.
Apply silicone grease on
weatherstrips to make them last
longer, seal better, and not stick or
squeak. See
Use a stiff brush with tire cleaner to
clean the tires.
.