Pontiac Vibe 2003 Owner's Manual page 278

What to Use
-
Use a mixture of one half clean, drinkable water and
-
one half coolant that meets GM Specification 1825
which won't damage aluminum parts. You can also use a
recycled coolant conforming to GM Specification 1825
with a complete coolant flush and refill. 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 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 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 the
proper coolant.
6-32
NOTICE:
-
M,
If you use an improper coolant mixture, your
- engine could overheat and be badly damaged.
M
The repair cost wouldn't be covered by your
warranty. Too much water in the mixture can
freeze and crack the engine, radiator, heater core
and other parts.
If you have to add coolant more than four times a year,
have your dealer check your cooling system.
NOTICE:
If 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.