GMC 2005 T-Series Owner's Manual page 180

How to Add Coolant to the Coolant
Surge Tank
If you have not found a problem yet, but the coolant level
is not at the COLD FULL mark, add a 50/50 mixture of
clean, drinkable water and DEX-COOL
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:
CAUTION:
{
Steam and scalding liquids from a hot cooling
system can blow out and burn you badly. They
are under pressure, and if you turn the coolant
surge tank pressure cap — even a little — they
can come out at high speed. Never turn the
cap when the cooling system, including the
coolant surge tank pressure cap, is hot. Wait
for the cooling system and coolant surge tank
pressure cap to cool if you ever have to turn
the pressure cap.
5-30
®
coolant at the
Notice: In cold weather, water can freeze and crack
the engine, radiator, heater core and other parts.
Use the recommended coolant and the proper
coolant mixture.
CAUTION:
{
Adding only plain water to your cooling
system can be dangerous. Plain water, or
some other liquid such as alcohol, can boil
before the proper coolant mixture will. Your
vehicle's coolant warning system is set for the
proper coolant mixture. With plain water or the
wrong mixture, your engine could get too hot
but you would not get the overheat warning.
Your engine could catch fire and you or others
could be burned. Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
®
coolant.