Pontiac G6 2010 Owner's Manual page 302

3. Fill the coolant surge tank with the proper mixture
to the FULL COLD mark. Wait about five minutes
and 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.
6-34
2. 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 might 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. Replace the pressure cap. Be sure the pressure
cap is hand-tight and fully seated.
Notice: If the pressure cap is not tightly installed,
coolant loss and possible engine damage may
occur. Be sure the cap is properly and tightly
secured.
If coolant is needed, add the proper DEX-COOL
coolant mixture at the coolant recovery tank.
®