1997 GMC Sonoma Owner's Manual - Page 263

A 50/50 mixture of water and DEX-COOL@ coolant for your vehicle will: What to Use Use a mixture of one-half clean wafer (preferably distilled) and one-half DEX-COOL@ coolant which won't damage aluminum parts. If you use this mixture, you don't need to add anything else. Give freezing protection down to -34°F (-37°C). Give boiling protection up to 265°F ( 1 29°C). 0 Protect against rust and corrosion. Help keep the proper engine temperature. Let the warning lights and gages work as they should. I NOTICE: When adding coolant, it is important that use you only DEX-COOL@(silicate-free) coolant. If coolant other than DEX-COOL@ is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner at 30,000 miles (50 000 km) or24 months, whichever occurs first. Damage caused the use by of coolant other than DEX-COOL@ not is covered by your new vehicle warranty. -- 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 With mix. plain water or the wrong mix, your engine could get too hot butyou wouldn't get the overheat you warning. Your engine could catch fire and or others could be burned. a 50/50 mix of clean Use water and DEX-COOL@ coolant. 6-25