Black plate (26,1)Cadillac STS Owner Manual - 2011What to Use{ WARNING:Adding only plain water or some other liquid to thecooling system can be dangerous. Plain waterand other liquids, can boil before the propercoolant mixture will. The vehicle's coolant warningsystem is set for the proper coolant mixture. Withplain water or the wrong mixture, the engine couldget too hot but you would not get the overheatwarning. The engine could catch fire and you orothers could be burned. Use a 50/50 mixture ofclean, drinkable water and DEX-COOL coolant.Use a 50/50 mixture of clean, drinkable water andDEX-COOL ® coolant. If using this mixture, nothing elseneeds to be added. This mixture:. Gives freezing protection down to −34°F (−37°C),outside temperature.. Gives boiling protection up to 265°F (129°C),engine temperature.. Protects against rust and corrosion.. Will not damage aluminum parts.. Helps keep the proper engine temperature.Notice: If an improper coolant mixture is used, theengine could overheat and be badly damaged. Therepair cost would not be covered by the vehiclewarranty. Too much water in the mixture can freezeand crack the engine, radiator, heater core, andother parts.Notice: If extra inhibitors and/or additives are usedin the vehicle's cooling system, the vehicle could bedamaged. Use only the proper mixture of the enginecoolant listed in this manual for the cooling system.See Recommended Fluids and Lubricants onpage 7‑9 for more information.6-26