1999 Chevrolet Prizm Owner's Manual - Page 241

yellowblue Radiator Pressure Cap NOTICE: Your radiator cap is a 15 psi (105 kPa) pressure-type cap and must be tightly installed to prevent coolant loss and possible engine damage from overheating. Be sure the arrows on the cap line up with the overflow tube on the radiator filler neck. Engine Coolant The following explains your cooling system and how to add coolant when it is low. If you have a problem with engine overheating, see "Engine Overheating" in the Index. A 50/50 mixture of clean, drinkable water and the proper coolant will: Thermostat Engine coolant temperature is controlled by a thermostat in the engine coolant system. The thermostat stops the flow of coolant through the radiator until the coolant reaches a preset temperature. When you replace your thermostat, a General MotorsR thermostat is recommended. D D D D D Give freezing protection down to -34_F (-37_C). Give boiling protection up to 265_F (129_C). Protect against rust and corrosion. Help keep the proper engine temperature. Let the warning lights and gages work as they should. What to Use Use a mixture of one-half clean, drinkable water and one-half coolant that meets GM Specification 1825-M, which won't damage aluminum parts. You can also use a recycled coolant conforming to GM Specification 1825-M with a complete coolant flush and refill. If you use this coolant mixture, you don't need to add anything else. 6-23