2006 Pontiac G6 Owner's Manual - Page 304

2. Then keep turning the pressure cap slowly, and remove it. 4. With the coolant surge tank pressure cap off, start the engine and let it run until you can feel the upper radiator hose getting hot. Watch out for the engine cooling fans. By this time, the coolant level inside the coolant surge tank may be lower. If the level is lower than the FULL COLD mark, add more of the proper mixture to the coolant surge tank until the level reaches the FULL COLD mark. 5. Then replace the pressure cap. Be sure the pressure cap is hand-tight and fully seated. 3. Fill the coolant surge tank with the proper mixture, to the FULL COLD mark. Wait about five minutes, then check to see if the level is below the mark. If the level is below the FULL COLD mark, add additional coolant to bring the level up to the mark. Repeat this procedure until the level remains constant at the FULL COLD mark for at least five minutes. 5-36