GMC Envoy Owner's Manual page 377

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.
5-34
®
4. Then fill the coolant recovery tank to the FULL
COLD mark.
5. Put the cap back on the coolant recovery tank,
but leave the radiator pressure cap off.