Saturn 2009 ASTRA - Manual (Page 199)

{ CAUTION
You can be burned if you spill
coolant on hot engine parts.
Coolant contains ethylene glycol
and it will burn if the engine parts
are hot enough. Do not spill
coolant on a hot engine.
1. Remove the coolant reservoir
pressure cap when the cooling
system, including the coolant
reservoir pressure cap and upper
radiator hose, is no longer hot.
Turn the coolant reservoir
pressure cap slowly
counterclockwise about two or
two and one-half turns.
If you hear a hiss, wait for that
to stop. This will allow any
pressure still left to be vented
out the discharge hose.
2. Keep turning the coolant
reservoir pressure cap slowly,
and remove it.
3. Fill the coolant reservoir with
the proper mixture, to the
KALT/COLD mark. Wait about
five minutes, then check to see
if the level is below the mark.
If the level is below the
KALT/COLD mark, add additional
coolant to bring the level up to
the mark. Repeat this procedure
until the level remains constant
at the KALT/COLD mark for
at least five minutes.
4. With the coolant reservoir
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 reservoir might
be lower. If the level is lower
than the KALT/COLD mark,
add more of the proper
mixture to the coolant reservoir
until the level reaches the
KALT/COLD mark.
5. Replace the coolant reservoir
pressure cap. Be sure the
pressure cap is hand-tight and
fully seated.
Coolant Reservoir Pressure Cap
Vehicle Service and Care 9-15