Here is my understanding of thermostats. 160 is lower operating temp in the summer, but you will get very little heat in the winter. 195 gets you nice and toasty in the winter but runs a bit hotter in the summer. 180 is the best of both worlds, you get ample heat in the winter and not running that hot in the summer. I have personally experienced all of these conditions here in Chicago. From what I have read over the years, in a properly operating cooling system the thermostat opens and closes as needed. When it opens the cooler water in the radiator flows into the engine as the hotter water flows into the radiator. The cooler water in the engine then causes the thermostat to close, allowing the cooler water to heat to the temp of the thermostat and keeping the hot water in the radiator so that the fan has a chance to cool it. The cycle continues. Hot rodders in the 60's & 70's would remove thermostats to try and run cooler but the water (coolant) ran unrestricted through the radiator not having a chance to stay in the radiator to cool down. Several aftermarket performance companys make restrictors that replace the thermostat with a block off plate with a small hole in the middle. I'm sure some people will disagree with me.