[srmmmm]

I've run a 180 thermostat with a 1/16" hole forever to allow some heated water on the backside of the thermostat which always seemed to reduce the engine temperature swings during extreme cold temperatures. Without it, it seemed the thermostat would "pop" open at temp, then I'd immediately lose 25-30 degrees as cold water from the radiator hit the engine. With the hole, the engine didn't reach operating temperature quite as fast, but the thermostat seemed to open smoother, avoiding the cold water shock.