2008 Buick LaCrosse Owner's Manual - Page 309

How to Add Coolant to the Radiator (3.8L V6 Engine) Notice: Your engine has a specific radiator fill procedure. Failure to follow this procedure could cause your engine to overheat and be severely damaged. 1. You can remove the radiator pressure cap when the cooling system, including the radiator pressure cap and upper radiator hose, is no longer hot. 5. Then fill the coolant recovery tank to the COLD FILL line. 6. Reinstall the coolant recovery tank cap and the pressure cap. 7. If the coolant in the recovery tank is constantly low, you should have your dealer/retailer service department inspect the vehicle for leaks. Turn the pressure cap slowly counterclockwise until it first stops. Do not press down while turning the pressure cap. If you hear a hiss, wait for that to stop. A hiss means there is still some pressure left. 5-39