GMC 2003 Sierra - Manual (Page 409)

What to Use
Use a mixture Qt one-haif dean, drinkabfe ivsiprand
one-hglf DEX-COOL® coolant which won't damage
aluminum parts.
\t you use this coolant mixture,
you don't need to add anything else.
A CAUTION:
Adding only plain water to your cooling
$ystern can be dangorouB, Plain waler^ or
some other liquid such as alcohol, can bait
before the proper coolant rninture wili^ Your
vehicle's coolant warning system is snt tor the
proper cootant miKture. With plain water or the
wrong mixture, your engine could gel too hot
but you wouldn't get the overheat warning.
Your engine could catch fire and you or others
could be burned. Use a 50/50 mixture ol clean,
drinkable water and DEK-COOL* coolant-
Notice: If you use an improper coolant mixture,
your engine could overheat and be badly damaged.
The repair cost wouldn't be covered by your
warranty. Too much water in the mixture can freeze
and crack the engine, imdlatorr heater core and
other parts.
5‘34 ------------------------------------------------------------------
If ynu have to add coolani more Than tour times a year,
have your dealer check yqur cooling system.
Wofjce: tf you use the proper coolant, you don't
have to add extra inhibitors or additives which claim
to improve the system. These can be harmful.
Checking Coolani
Tha cooianT surge tank fs
focated in the engine
compartment on Ihe
passenger's side of the
vehida. See
Engine
Compadment 0v9rviev\> on
page 5 - 1 2 for more
irfornnalFon on location.