I've read most of this post and some of you are under the impression that the engineers who build these things design it to be the best that it can be. ( Wrong! )
They design the engines to operate at high temps so they can pass epa guidelines. Also no one has said anything about the thermostats operation other than the temperature that it begins to open. How fast it goes from full closed to full open and the rate of coolant flow, or how much the thermostat restricts flow are also just as important. That is why the so called performance thermostats are usually 180s and usually flow better.

 

I agree with that.
Along with the fact that Jeep has to build a truck that can be sold in Michigan and Texas. They have to find a middle ground for things to operate in both extremes. Does it work, sure....is it the best possible combo for each extreme, no.
10w30 motor oil, works year round in most climates, but in extreme cold maybe 5w30 would be a better choice, just like I run 10w40 in the Texas 100+ summers.

I guess the root mentality is the true division, not the degree of the thermostat. Every car forum I've been on has had 3 groups of people.
(using an example part)

1. "I will only buy an OEM Mopar oil filter."

2. "It doesn't matter, throw any ole filter from Joe Bob's Auto on there."

3. "I heard if you retrofit part#12345 on there, you can hold an extra quart and have more filter area and better flow characteristics."

I myself am a #3 and run a Mr. Gasket 180* #4364 and will not turn back.

 

The EPA is not why Ferarri's run at 212 degrees, or why Jeeps ran at 210 in 1960.

 

That is completely backwards as far as I am concerned. The job of the thermostat is actually to hold coolant in the radiator to give it sufficient time to cool off before returning to the engine to reabsorb the heat and return to the radiator again to be cooled.
To everyone who says that it was designed that way so it must be the only way. Your suspension was also designed at the factory, many of us decided that it did not suit our needs so we modified it so it did.
When the Cherokee was produced it was not the factorys main objective to have it crawling through the rocks/woods. Its main concern was emissions and driveability/economy.
I think running a lower stat is a great idea. One of the largest factors of longevity is temperature. One of the other benefits is that if the radiator is cooler, this means the coolant cooling the trans is cooler. If the trans is cooler its much happier.
The only downfall is actually keeping the temp down. Opening the thermostat early will not do anything if there is no means to cool what is in the radiator while it is holding there. so if the fan is not coming on, or working properly, it may actually run hotter from not being able to close and not holding coolant in the radiator long enough to be cooled.
So my plan is to find a comparable switch for the electric fan and see how it goes, or completely remove both fans and install 2 electric fans.
Its early and I hope I make sense. my $.02

 

THAT is completely backwards.

 

I've used 180 Ts in different computer controlled cars just to see the effect.It always resulted in less fuel mileage and less throttle response.The PCM was programed using the 195 Ts,anything else is going to change the PCM operation. By the way ALL of todays systems will ADD fuel and reduce timing to help cool the engine if it gets too hot. So don't worry about it and run your 195 Ts.

As said above, stay with the 195 thermostat. The engine runs above that temp normally anyway so both the 180 and 195 degree thermostats would be wide-open no matter what so running a 180 isn't going to force the engine to run any cooler. And the 195 thermostat helps the engine warm up faster and get it out of its full-rich open loop mode. This will not make much of a difference in temperate or warm climates but it sure will if you live in a very cold part of the nation.

There is absolutely NO advantage in a computer-controlled engine to running a cooler thermostat than the engine and computer was designed to run with. The lower temperature makes the ECU think it's not warmed up, so it runs rich=less gas mileage.

This isnt an opinionated argument. Its about the facts.

 

Dugualla is exactly correct. The stat is there to allow the system to heat up as quickly as possible so it can get into closed loop mode/reach the point that the carb is jetted for.

Oh, and I use Amsoil 10W30 and change it every 10,000 miles.

 

Strange how all the performance catalogs list 160F and 180F t-stats for the GM LS engines and (the new) Chrysler HEMI engines to improve performance. There missing the boat by not offering a 195F t-stat. Wonder why our '09 Corolla comes from the factory with a 180F t-stat, our '06 Vue (Honda VTEC) has a factory 170F t-stat and our '05 Ponyota Vibe is 180F from the factory?????

 

Stores also promote high flow cats, throttle body spacers, short rams, etc.

Your point?

 

I am glad that 4 pages has finally settled this. If you haven't decided one way or the other try both, see how it affects your vehicle.

 

I have......our '98 XJ had a 195F t-stat when we bought it from the city fleet early December '09. Never saw 210F on the ScanGauge, would seldom see 200F, cold outside. Mid/late December started all the under hood R&R, including replacing the 195F t-stat with a Stant SuperStat 180F (the one that's stainless steel). ScanGauge indicated coolant temp was running 10-15 degrees cooler (180F-185F as expected), heater still toasty and a couple of times dividing the gallons pumped in into the miles driven (all city) yielded 15-17 mpg. When the kiddo drove it back to school (70-75 mph), 1st hwy mpg fill-up was 21.4, second was 22.1 mpg.

In the past 40+ years of owning/hot rodding/engine building/farting around with numerous vehicles, if a 180F t-stat was available at the parts store, that's what I put them and never had any issues. Nine months out of the year a 180F t-stat in the XJ will allow the coolant to run a little cooler vs a 195F t-stat. This time of year (hot summer), a 180 t-stat won't run any cooler than a 195 t-stat in the XJ, the rad is too small. Cooler weather is just around the corner, I hope.

 

Far be it for me to try and convince someone of anything. I use the 195 because as I see it that is how it is supposed to be setup. I don't think anyway is "wrong" but I just don't see the purpose of the lower temp stat. The engine is going to find it's happy spot unless something is wrong internaly or the cooling system is compromised somehow.

 

Apropos very little, from my ride home today, 91 degrees ambient.

(I don't know what stat this '97 has in it. The entire system was new about nine months prior to my purchase form the PO.

No AC., this is normal running temp.



AC, highway speed:



AC after a traffic backup:



AC after back at highway speed:



AC, stop & go on surface streets:



Worst case. AC, idling in my driveway for 15 minutes:



No drama here.

 

That's my whole point about the factory gauge.......almost motionless under conditions that really tax the cooling system. Same way on our other vehicles with factory gauges......needle goes to a point between C & H and sits there but all is well.

I'm curious - Under the exact same conditions, if u were to turn off the a/c after idling in the drive way for 15 minutes, would your efan still be running?

 

Actually I noted that. The electric fan turned off immediately when I switched to vent. It does not seem to be temperature sensed, merely tied to the A/C switch.