How do you change the thermostat on a 1994 Buick Roadmaster?

Should be located in housing at engine end of upper radiator hose. Drain about 1 gallon of coolant from radiator Remove this housing Make note how thermostat is installed Clean both surfaces Replace thermostat and gasket Re-fill coolant slowly to prevent "airlock" Start vehicle check for leaks Run vehicle to normal operating temperature with heater on Check coolant level