2003 Cadillac DeVille Owner's Manual - Page 303

I f no coolant is visible in the surge tank, add coolant as follows: Steam and scalding lq i, i u, from a hot cool J system can blow out and burn you badly. They are under pressure, and if you turn the coolant surge tank pressure cap even a little-- they can come outat high speed. Never turn the cap when the cooling system, including the coolant surge tank pressurecap, is hot. Wait for the cooling system and coolant surge tank pressure cap to cool if you ever have to turn the pressure cap. -- Adding only plain water to your cooling system can be dangerous. Plainwater, or some other liquid suchas alcohol, can boil before the proper coolant mixturewill. Your CAUTION: (Continued) 5-32