Chevrolet 1994 Astro Passenger Owner's Manual page 278

Protecting Exterior Bright Metal Parts
Bright metal parts should be cleaned regularly to keep their luster. Washing
with water is all that is usually needed. However, you may use GM Chrome
Polish on chrome or stainless steel trim, if necessary.
Use special care with aluminum trim. To avoid damaging protective trim,
never use auto or chrome polish, steam or caustic soap to clean aluminum.
A coating of wax, rubbed to high polish, is recommended for all bright
metal parts.
Aluminum Wheels (If So Equipped)
Your aluminum wheels have a protective coating similar to the painted
surface of your vehicle. Don't use strong soaps, chemicals, chrome polish,
abrasive cleaners or abrasive cleaning brushes on them because you could
damage this coating. After rinsing thoroughly, a wax may be applied.
NOTICE:
If you have aluminum wheels, don't use an automatic vehicle
wash that has hard silicon carbide cleaning brushes. These
brushes can take off the protective coating.
Weatherstrips
Silicone grease on weatherstrips will make them last longer, seal better, and
not stick or squeak. Apply silicone grease with a clean cloth at least every
six months. During very cold, damp weather more frequent application may
be required. (See "Recommended Fluids & Lubricants" in the Index.)
Sheet Metal Damage
If your vehicle is damaged and requires sheet metal repair or replacement,
make sure the body repair shop applies anti-corrosion material to the parts
repaired or replaced to restore corrosion protection.
Foreign Material
Calcium chloride and other salts, ice melting agents, road oil and tar, tree
sap, bird droppings, chemicals from industrial chimneys, and other foreign
matter can damage your vehicle's finish if they remain on painted surfaces.
Use cleaners that are marked safe for painted surfaces to remove foreign
matter.