Pontiac G3 2010 Owner's Manual page 253

2. Then keep turning the pressure cap slowly and 3. Fill the coolant surge tank with the proper mixture
remove it. to the Maximum mark on the coolant surge tank.
Wait about five minutes, then check to see if the
level is below the mark. If the level is below the
Maximum mark, add additional coolant to bring the
level up to the mark.
Repeat this procedure until the level remains
constant at the Maximum mark for at least
five minutes.
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