1995 GMC Sonoma Owner's Manual - Page 242

When you replace your radiator pressure cap, a GM cap is recommended. See "Service Replacement Part and Filter Recommendations" in the Index. Thermostat Engine coolant temperature is controlled by a thermostat in the engine coolant system. Thethermostat stops the flow of coolant through the radiator until the coolant reaches a preset temperature. When you replace your thermostat, an AC@thermostat is recommended. Power Steering Fluid 1 Ad 6-24