Cadillac 2003 DeVille Owner's Manual page 296

Adding only
pain
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 DEX-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, 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.
The engine coolant surge tank is located toward the
rear of the engine compartment on the passenger's side
of the vehicle. For more information on location, see
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p?gs 5-?2. .
Notices If you use the proper coolant, you don't
have
i o
add extra inhibitors or additives which claim
to improve the system. These can be harmful.
5-25