1998 GMC Sonoma Owner's Manual - Page 306

WeatF -!rs ips Silicone greaseon 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 Tndex.) Cleaning the Outsideof Your Vehicle The paint finish on your vehicle provides beauty, depth of color, gloss retention and durability. Don't wash your vehicle in the direct rays of the sun. Don't use strong soaps or chemical detergents. Use liquid hand, dish or car washing (mild detergent) soaps. You can get GM-approved cleaning products from your dealer. (See "Appearance Care and Materials" in the Index.) Don't use cleaning agents that are petroleum based, or that contain acid or abrasives. All cleaning agents should be flushed promptly and not allowed to dry on the surface, or 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 your vehicle. Washing Your Vehicle The best way to preserve your vehicle's finish is to keep it clean by washing it often with lukewarm or cold water. Cleaning Exterior LampsLenses Use lukewarm or cold water, a soft cloth and a liquid hand, dish or car washing (mild detergent) soap toclean exterior lamps and lenses. Follow instructions under "Washing Your Vehicle." 6-56