GMC 2004 Envoy Owner's Manual page 343

3. Fill the radiator with the proper DEX-COOL
coolant mixture, up to the base of the filler
neck. See Engine Coolant on page 5-24 for more
information about the proper coolant mixture.
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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.
5-35