Buick 2003 Regal Owner's Manual page 230

What to Use
Use a mixture of one-half clean, drinkable water and
one-half DEX-COOL@ coolant which won't damage
aluminum parts. If you use this coolant mixture,
you don" -eed to add anything else.
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.
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 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.
Checking Coolant
The engine coolant recovery tank is located on the
passenger's side of the vehicle at the rear of the engine
compartment. See Engine Compartment Overview on
page 5-12 for more information on location.
The vehicle must be on a
level surface. When your
engine is cold, the
coolant level should be at
the COLD mark or a
little higher. When your
engine is warm, the
level should be up to the
HOT mark or a little higher.
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