160F (71C) THERMOSTAT, 4-cyl (except Mk4)

The standard cooling system is very trouble-free from the factory. The radiator capacity is more than adequate for the horsepower produced by even a high-output forced-induction engine, or a high-compression large displacement engine towing a trailer. We feel that for most applications, the stock 189 degree (4cyl) thermostat and 198 degree fan switch are adequate, and that the operating temperature designed by the factory helps to ensure good mileage. VR6 models, by the way, come factory equipped with a 180 degree thermostat, but still use a 203 degree/216degree or higher fan switch. For certain applications, you may feel that a reduction in cooling system temperature is needed. Be sure to check the condition of your water pump and the pressure cap.