WARNING!
Adding only plain water or some other liquid to the cooling system can be dangerous. Plain water and other liquids can boil before the proper coolant mixture will.
The coolant warning system is set for the proper coolant mixture.
With plain water or the wrong mixture, the engine could get too hot but you would not get the overheat warning. The engine could catch fire and you or others could be burned. Use a 50/50 mixture of clean, drinkable water and DEX-COOL coolant for non-eAssist engine(s). Use a 50/50 mixture of deionized water and DEX-COOL coolant for eAssist engine(s).

Use a 50/50 mixture of deionized water or clean, drinkable water and DEX-COOL coolant. If using this mixture, nothing else needs to be added.

This mixture:

• Gives freezing protection down to −37°C (−34°F), outside temperature.

• Gives boiling protection up to 129°C (265°F), 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, the engine could overheat and be badly damaged.
The repair cost would not be covered by the vehicle warranty.
Too much deionized water or clean, drinkable water in the mixture can freeze and crack the engine, radiator, heater core, and other parts.

Never dispose of engine coolant by putting it in the trash, pouring it on the ground, or into sewers, streams, or bodies of water. Have the coolant changed by an authorized service center, familiar with legal requirements regarding used coolant disposal. This will help protect the environment and your health.