GMC 1997 Safari Owner's Manual page 311

Cleaning the Outside of the Windshield,
Backglass and Wiper Blades
If the windshield is not clear after using the windshield
washer, or if the wiper blade chatters when running, wax,
sap or other material may be on the blade or windshield.
Clean the outside of the windshield with GM
Windshield Cleaner, Bon-Ami@ Powder
(non-scratching glass cleaning powder), GM Part
No. 105001 1. The windshield is clean if beads do not
form when you rinse it with water.
Grime from the windshield will stick to the wiper blades
and affect their performance. Clean the blade by wiping
vigorously with a cloth soaked in full-strength windshield
washer solvent. Then rinse the blade with water.
Check the wiper blades and clean them as necessary;
replace worn blades.
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 and Lubricants" in the Index.)
Cleaning the Outside of Your Vehicle
The paint finish on your vehicle provides beauty, depth
of color, gloss retention and durability.