Chevrolet 2003 Avalanche Owner's Manual page 365

HOW to Add Coolant to the Coolant
Surge Tank
If you haven't found a problem yet, check to see if
coolant is visible in the surge tank. If coolant is visible
but the coolant level isn't at the FULL COLD mark, add a
50/50 mixture of clean, drinkable
water
and DEX-COOL@
coolant at the coolant surge tank, but be sure the
cooling system, including the coolant surge tank
pressure cap, is cool before you do it. See Engine
Coolant on page 5-24 for more information.
If no coolant is visible in the surge tank, add coolant as
follows:
Steam and scalding liquids from a hot co ng
system can blow out and burn you badly. rney
are under pressure, and if you turn the radiator
pressure cap
--
even a little
--
they can come
out at high speed. Never turn the cap when the
cooling system, including the radiator pressure
cap, is hot. Wait for the cooling system and
radiator pressure cap to cool if you ever have
to turn the pressure cap.
5-32