2005 Pontiac Grand Prix Owner's Manual - Page 327

11. By this time, the coolant level inside the radiator filler neck may be lower. If the level is lower, add more of the proper DEX-COOL® coolant mixture through the filler neck until the level reaches the base of the filler neck. 12. Then replace the radiator pressure cap. At any time during this procedure if coolant begins to flow out of the filler neck, reinstall the pressure cap. Be sure the pressure cap is hand-tight and fully seated. 13. Check the coolant in the recovery tank. The level in the coolant recovery tank should be at the HOT mark when the engine is hot or at the FULL COLD mark when the engine is cold. 10. Start the engine and let it run until you can feel the upper radiator hose getting hot. Watch out for the engine cooling fan(s). 5-37