Chevrolet 2003 Blazer Owner's Manual page 296

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 5-23 for more
information about the proper coolant mixture.
5-33