I replaced my faulty thermostat this weekend, as the temperature needle would generally hover around 75-80 deg C instead of 90. Obviously your engine is in danger of overheating if you have a stat that likes to stay closed, however mine had the opposite problem, meaning the engine coolant was generally running too 'cool'. So, I was just wondering how beneficial this actually was to the car, i.e. what this now changes? All I can think of is: 1 - The heaters will warm up abit sooner 2 - Very very marginal fuel savings Anyone got any other disadvantages of an engine running too 'cool'?