These thermostats lock open if they fail to help protect your engine!
 
160 is a good thermostat for a stock engine in a hot climate.
 
180 thermostats are good for cold weather driving.
 
195 is the thermostat to use for a competition engine. Remember that heat produces power. the engine will come up to operating temperature faster with a high temperature thermostat. If you engine is tuned correctly - timing and fuel mixture - the higher temperature is the way to go.