GMC 2009 Savana - Manual (Page 271)

1. You can remove the radiator pressure cap when
the cooling system, including the radiator pressure
cap and upper radiator hose, is no longer hot.
Turn the pressure cap slowly counterclockwise until
it first stops. Do not press down while turning the
pressure cap.
If you hear a hiss, wait for that to stop. A hiss
means there is still some pressure left.
2. Then keep turning the pressure cap, but now push
down as you turn it. Remove the pressure cap.
3. Fill the radiator with the proper DEX-COOL ®
coolant mixture, up to the base of the filler
neck. See Engine Coolant on page 5-25 for more
information about the proper coolant mixture.
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