Pontiac 2003 Bonneville Owner's Manual page 298

9. Put the cap back on the coolant recovery tank, but
leave the radiator pressure cap off.
11. By this time, the coolant level inside the radiator
filler neck may be lower. If the level is lower, add
more of the proper DEX-COOL@ coolant mixture
through the filler neck until the level reaches
the base of the filler neck.
12. Then replace the
pressure cap. At any
time during this
procedure if coolant
begins to flow out
of the filler neck,
reinstall the
pressure cap.
IO. Start the engine and let it run until you can feel the
upper radiator hose getting hot. Watch out for the
engine cooling fans.
Be sure the arrow on the pressure cap lines
up like this.
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