Jeep Thermostats ????

Can anyone tell me why the Jeep company (and Jeepers in general) install a 195* thermostat in the Jeeps. I recently changed out my OEM (plastic and cracked) radiator with an all metal radiator.

I figured that since I was changing the radiator that I would go ahead and change the thermostat too. When I went to the parts store they asked me which temperature thermostat (165*, 185*, or 195*).

I purchased and installed the 165* thermostat because I plan on heading out to the desert this summer and figured that a cooler thermostat would equate to a cooler engine temp in the desert.

My temp gauge stays around 170* or so while driving around Southern California now and my oil pressure gauge is not flexuating all over now either (stays around 30-40 psi). I know that oil temps corrilates to engine temp so that is why the oil steadied out.

So why do we still replace those old thermostats with the 195* stats and not the 165* if everyone states 200-210 is normal for a Jeep?

Fuel economy. The temp sensor tells the computer what temp the engine is and the commputer decides how much fuel to inject based on that info. At 165, the engine thinks its still in warmup mode, and adds more fuel. The engine is designed to run at its most efficient around 200-210, thats not to say you will see much of a difference down as low as 180 or even 170, but thats the reason.
I ran a 180 in my XJ for a couple years and didnt like it because of the huge fluctuations. While driving, it would go down to 180 but while stopped in traffic or a drivethrough, it would go up to 210. I eventually put a 195 back in so it wouldnt fluctuate so much, 195 while driving and still 210 while at rest.
I think you will find that it will only stay cooler with the lower stat while you are moving and still get up to 200 or so while sitting still for any period.