2001 Cadillac DeVille Owner's Manual - Page 334

Checking Coolant CAUTION: Turning the surge tank pressure cap when the engine and radiator are hot can allow steam and scalding liquids to blow out and burn you badly. Never turn the surge tank pressure cap -- even a little -- when the engine and radiator are hot. The vehicle must be on a level surface. When your engine is cold, the coolant level should be at the FULL COLD mark, located on the side of the surge tank that faces the engine. The surge tank is located on the passenger's side of the engine. For more information on location, see "Engine Compartment Overview" in the Index. The cooling system is under a lot of pressure when it is hot. If the CHECK COOLANT LEVEL message appears on the Driver Information Center (DIC), you will need to add coolant. If the CHECK COOLANT LEVEL message comes on and stays on, it means you're low on engine coolant. For more information, see "Check Coolant Level Message" in the Index. 6-26