here in lies the thermostat...

the truth - it's not a thermostat. It's a heat valve. Once it gets up to temp, it opens. It's that easy.

If the engine gets too hot, the t-stat won't cool it back down. Only the fans can do that. And that isn't even a guarantee. Air temp, flow issues all come into play.

Now... it's obvious what happens when an engine overheats. but people never think about under heated engines. Now, this is a more modern problem, mostly caused by the nature of better machining and tighter tolerances. Add in the fact that different metals expand and contract at different rates, an overly cool engine can prematurely wear.

Next comes the real knee slapper - a warmer engine runs more efficiently. Yes. It does. the compression event happens more efficiently than does a colder engine. Now, the air DOES need to be cold coming in, but a properly warmed engine isn't the enemy of power people want you to believe.