1999 GMC Sonoma Owner's Manual - Page 266

yellowblue Checking Coolant CAUTION: Turning the radiator pressure cap when the engine and radiator are hot can allow steam and scalding liquids to blow out and burn you badly. With the coolant recovery tank, you will almost never have to add coolant at the radiator. Never turn the radiator pressure cap -- even a little -- when the engine and radiator are hot. Add coolant mixture at the recovery tank, but be careful not to spill it. The vehicle must be on a level surface. When your engine is cold, the coolant level should be at ADD, or a little higher. When your engine is warm, the level should be up to FULL HOT, or a little higher. Adding Coolant If you need more coolant, add the proper DEX-COOLR coolant mixture at the coolant recovery tank. CAUTION: You can be burned if you spill coolant on hot engine parts. Coolant contains ethylene glycol, and it will burn if the engine parts are hot enough. Don't spill coolant on a hot engine. 6-28