2003 Cadillac Seville Owner's Manual - Page 277

Checking Coolant Turning the surge tank pressure cap wherre 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, which is at or above the fill mark at the forward edge of the surge tank. The engine coolant surge tank is located in the engine compartment on the driver's side of the vehicle. See 5-74for more Engine Compartment Overview on page information on location. If the CHECK COOLANT LEVEL message comes on and stays on, it means you're low on engine coolant. 5-28