1995 Pontiac Bonneville Owner's Manual - Page 237

To Add Coolant Radiator Pressure Cap NOTICE: Your radiator capis a 15 psi (105 kPa) pressure-type cap and must be tightly installed to prevent coolantloss and possible engine damage from overheating. Be sure the arrows on the cap line up with the overflow tube on the radiator filler neck. When you replace your radiator pressure cap, an AC@ cap is recommended. If you need more coolant, add the proper mix at the coolant recoverytank. Thermostat Add coolant mix at recovery tank, but be careful not the to spill it. Engine coolant temperature is controlled by a thermostat in the engine coolant system. The thermostat stops the flow of coolant through theradiator until the coolant reaches a preset temperature. When you replace your thermostat, an AC@thermostat is recommended. 6-24