GMC 1999 Suburban, Owner'S Manual, Page: 306 / 424

yellow blue
6-26
NOTICE: (Continued)
engine coolant will require change sooner
--
at
30,000 miles (50 000 km) or 24 months,
whichever occurs first. Damage caused by the use
of coolant other than DEX
-
COOL
R
is not
covered by your new vehicle warranty.
What to Use
Use a mixture of one
-
half clean, drinkable water and
one
-
half DEX
-
COOL
R
coolant which won’t damage
aluminum parts. If you use this coolant mixture, you
don’t need to add anything else.
CAUTION:
Adding only plain water to your cooling system
can be dangerous. Plain water, or some other
liquid like 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 wouldn’t
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
R
coolant.