Cadillac 1996 DeVille Owner's Manual page 244

A
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 mix will. Your vehicle's coolant warning
system is set for the proper coolant mix. With
plain water or the wrong mix, 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 mix of clean
water and
DEX-COOL
TM
antifreeze.
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