Buick RIVIERA 1993 Manual page 260

Weatherstrips
-These are places where glass or metal meets rubber.
Silicone grease there will make them last longer, seal
better, and not squeak. Apply silicone grease with a
clean cloth at least every six months.
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 for these stains.
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 a major repair expense.
Minor chips and scratches can be repaired with touch-up
materials available fi-om your dealer or other service
outlets. Larger areas of finish damage can be corrected
in your dealer's body and paint shop.
Underbody Maintenance
Chemicals used for ice and snow removal and dust
control can collect on the underbody. If these are not
removed, accelerated corrosion (rust) can occur 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 other debris can collect. Dirt packed in closed areas
of the frame should be loosened before being flushed.
Your dealer or an underbody vehicle washing system
can do this for you.