1999 Cadillac Catera Owner's Manual - Page 261

yellowblue If you need more coolant, add the proper DEX-COOLR coolant mixture at the surge tank, but only when the engine is cool. Adding 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 KALT/COLD line (seam). If the light comes on and stays on, it means you're low on engine 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. When replacing the pressure cap, make sure it is hand-tight. For more information, see "Low Coolant Warning Light" in the Index. 6-23