Where is the thermostat for a 2000 Chevrolet Malibu v6?

The thermostat for a 2000 Chevrolet Malibu V6 is located on the engine, at the bottom of the engine. To be more precise, it's usually at the lower intake manifold or near the water pump. You'll need to consult a repair manual specific to your 2000 Malibu V6 engine (either the 3.1L or the 3.8L) for the exact location and details on how to access it. A visual inspection with the engine cool and the appropriate diagrams from a repair manual will be needed to pinpoint its location.