Just to clarify something here.... A thermostat does not and can not increase the cooling efficiency if the cooling system. The theory that slower movement of the coolant keeping the engine cooler couldn't be more false.
In order to cool a material it must come in contact with molecules of a colder substance be it water, air, ect. The greater the heat energy that you wish to absorb, the greater volume of heat absorber you need to contact that surface.
What cools you better in the summer, your fan in low or high?
What heats your car faster, fan in low or high? Btw the high setting is sucking air through the heater core faster than low.
As an extremely technical/nerdy mechanic/hd mechanic for almost 20 years, plus wrenching as a hobby in everything from sophisticated 4x4's, race cars, 3000hp blown alcohol engines, I can tell you from not only the scientific side but also experience that this theory is absolutely ludicrous.
There is one exception however where a thermostat can keep the engine cooler but it has nothing to do with slowing the water to keep it cool. It is the sliding sheath type thermostat that does more than simply let weather through when it's if temperature. Rather it redirects coolant flow for quicker warm ups without possibility of hotspots then closes the recurculatiry system and opens the flow to the radiator as required. If you remove this type of thermostat you can over heat due to the fact an uncontrolled amount if coolant is constantly recirculating without ever being cooled in the rad. This system is contrary to a typical passenger vehicle/atv/bike/sled thermostat/system which simply dead heads with small curculatory bleeders until the opening temperature is met.
Further more water wetter has never lowered temps by any detectable amount that I could measure via temp gauge and laser thermo gun, and believe me i tested it out of curiosity sake. Block radiator with cardboard, adjust idle screw to 2200rpm for 40minutes, after 15 or so minutes both the gauge and temp gun were reading 227 degrees. Shut it down,let it cool down, add water wetter and repeat. Exact same results. Could I be wrong, for could there be some great marketing for a useless product? You can decide for yourself.
