GMC 2009 Envoy Denali Owner's Manual page 331

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.
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.
5-29