Pontiac 2004 Sunfire Owner's Manual page 259

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.
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 fan.
5. Then replace the
pressure cap. Be sure
the pressure cap is
hand-tight and fully
seated. See your
dealer, if necessary.
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