Hotter is more effecient in terms of emissions. But cooler is more efficient in terms of making power. If the combustion chamber is cooler, you are able to put more air and fuel into it without having premature detonation (knock). The more air and fuel...the more power.

Yes, with computer controlled cars it is harder to change the thermostat out without encountering problems. But if you have access to a programmer, you can tune it in such a way that you don't have any problems. Even without one, the worst problem you can run into is a drop in mileage. I ran a 160* t-stat in my 99 Grand Prix for a few years. I noticed a 2mpg drop in mileage. After I re-programmed the computer to take advantage of the cooler t-stat, I gained over 1mpg back in mileage.

As mtndewnut pointed out, it also helps out if you sit in traffic a lot

 

I just pulled my 180 out and put the 195 back in and my truck is much happier. The 180 did cost me fuel millage and did not notice a big difference in power. I agree that heat can hurt a motor but running cold is not great either as too much fuel can seep into your oil and thin it causing a spun bearing (granted this is extreem but so is saying if you run at factory spec you are going to crack your heads). Also a thermostat when it reaches temp opens up regardless of the tempature range once it opens it is open so either way it can run hot the only difference is the 180 will open sooner. Just my 2 cents

Steve

 

I put a 180" in my Ram, im still getting 10 mpg...lol

 

securtis12, how much did it affect your fuel mileage? I'm on a quest to get 15 mpg out of my ram regularly and it would help to know how it affected your mileage.

 

According to what i read, 180 is acceptable by Dodge for optimal fuel burning, when u get into 160 then its start to affect computer curves

 

it stays in open loop mode and dumps a bunch of gas since the pcm thinks it's not at op temp yet

 

It cost me about 1 1and half around town not much diference on the road as it came up to temp anyway. I am going to go to synthetic in motor diferentials and transmission/transfer case that gave my son another 2. I got around 13 with the 180 and 14 to 14.5 with the 195 just back and forth to work.

Steve

 

pretty interesting. that tells me that if you add 15 deg to the ECT sensor reading, you should get better mileage. I might have to try that...

 

At 180 it stays in open loop mode? Never heard of that, like to read up on this! So If thats true over 200 would give you great gas mileage?

 

I think the threashold for open loop mode is around 170 deg. if it takes too long to get to 170, then it will throw a code.