1999 Pontiac Grand Prix Owner's Manual - Page 284

yellowblue Checking Coolant If this LOW COOLANT light comes on and stays on, it means you're low on engine coolant. If you need more coolant, add the proper DEX-COOLR coolant mixture at the coolant recovery tank, but be careful not to spill it. If the coolant recovery tank is completely empty, add coolant to the radiator. (See "Engine Overheating" in the Index.) The vehicle must be on a level surface. When your engine is cold, the coolant level should be at the COLD mark or a little higher. When your engine is warm, the level should be up to the HOT mark or a little higher. Adding Coolant 6-28