How do you change the thermostat on a 98 cabrio?

To change the thermostat on a 1998 VW Cabrio, start by ensuring the engine is cool. Drain the coolant from the system, then remove the upper radiator hose connected to the thermostat housing. Unbolt the thermostat housing, replace the old thermostat with a new one (making sure to align the small notch with the housing), and reassemble everything in reverse order. Finally, refill the coolant and check for leaks before starting the engine.