2001 Chevrolet Impala Owner's Manual - Page 314

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. 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. United States Canada If this LOW COOLANT LEVEL message 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. Adding Coolant 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. Occasionally check the coolant level in the radiator. For information on how to add coolant to the radiator, see "Cooling System" in the Index. 6-27