2006 Buick Lucerne Owner's Manual - Page 294

Checking Coolant (4.6L V8 Engine) The engine coolant surge tank is located toward the rear of the engine compartment on the passenger's side of the vehicle. 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. Adding Coolant If you need more coolant, add the proper DEX-COOL® coolant mixture at the coolant surge tank, but only when the engine is cool. {CAUTION: For more information on location, see Engine Compartment Overview on page 5-12. 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. Do not spill coolant on a hot engine. When replacing the pressure cap, make sure to turn the cap until it clicks. {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. 5-26