How do you change thermostat on 2002 gs 300 Lexus?

To change the thermostat on a 2002 Lexus GS 300, start by allowing the engine to cool, then disconnect the negative battery cable. Remove the radiator cap and drain the coolant, followed by removing the thermostat housing, which typically involves loosening the bolts holding it in place. Take out the old thermostat, clean the mating surfaces, and install the new thermostat with a new gasket. Finally, reassemble everything, refill the coolant, and reconnect the battery.