Pontiac 2007 G5 Owner's Manual page 296

296
2. Then keep turning
the pressure cap
slowly, and
remove it.
3. Fill the coolant surge tank with the proper
mixture, to the COLD FILL line. Wait about
five minutes, then check to see if the level
is below the COLD FILL line. If the level
is below the line, add additional coolant to
bring the level up to the line. Repeat this
procedure until the level remains constant at
the COLD FILL line for at least five minutes.