GMC 2003 Envoy XL Owner's Manual page 329

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