Engine Coolant - GMC SIERRA CK2 1999 Owner's Manual

The radiator pressure cap must be tightly installed with
the arrows on the cap lined up with the overflow tube on
the radiator filler neck.
NOTICE:
Your radiator cap is a 15 psi (105 kPa)
-
pressure type cap and must be tightly installed to
prevent coolant loss and possible engine damage
from overheating. Be sure the arrows on the cap
line up with the overflow tube on the radiator
filler neck.
Thermostat
Engine coolant temperature is controlled by a thermostat
in the engine coolant system. The thermostat stops the
flow of coolant through the radiator until the coolant
reaches a preset temperature.
When you replace your thermostat, an AC R thermostat
is recommended.
6-28

Engine Coolant

The cooling system in your vehicle is filled with
COOL R engine coolant. This coolant is designed
-
DEX
to remain in your vehicle for 5 years or 150,000 miles
(240 000 km), whichever occurs first, if you add only
COOL R extended life coolant.
-
DEX
The following explains your cooling system and how to
add coolant when it is low. If you have a problem with
engine overheating, see "Engine Overheating" in
the Index.
A 50/50 mixture of clean, drinkable water and
COOL R coolant will:
-
DEX
D
Give freezing protection down to
D
Give boiling protection up to 265
D
Protect against rust and corrosion.
D
Help keep the proper engine temperature.
D
Let the warning gages work as they should.
yellowblue
_ _
- -
34 F ( 37 C).
_ _
F (129 C).