I believe the thermostat in our engines is a 190F tstat. What is the downside, if any, of using a 180F tstat?

Thanks

 

I think 195 is stock. I run a 180 stat in the summertime. My temps always stay at least 10 degrees cooler than with the 195 stat. People claim that the engine is not as efficient when it's running that much cooler. That's fine with me as long as my truck isn't running hot. For me, the only drawback is that when it starts getting cold out the truck really never warms up. I just put my stocker back in because even after a 30 mile commute my temps barely reached 150 degrees. Once spring hits I will put the 180 unit back in...
My mileage and SOTP power are the same either way....

 

After I posted my original question, it occured to me I should have done a search first. So I did, and found several threads on the subject, with varying opinions. So, I emailed Cummins with the question and just received this reply:

Scott,
Your engine is designed to run in the 190 to 207 degree range with a maximum temperature of 225 degrees. The newer engines are designed to run at higher temperatures to more efficiently burn fuel for economy and emissions.

Certainly your engine will run with the cooler thermostat. The most noticeable affects will be reduced fuel mileage and more carbon build up in the engine. Which, over an extended period, could shorten the life of your engine.

 

been there done that, stay with stock t stat year around

 

This subject has been debated forever. Most people agree with what the Cummins guy told you. For me, on the other hand, I've been running this stat since 2003 in a couple different trucks and never had an issue other than a cooler running engine. My mileage does not change when I run it either. I'll just continue to be the odd guy......

 

Last winter on a trip across WY, I did some experimenting.

I ran with the winter cover fully closed, fully open, and removed. 75 miles across the flats of western WY.

Best mileage came from having the cover on and fully closed, and let the water temp rise. Seemed to run just a tad quieter, but that is subjective.

Since a diesel doesn't have an ignition system, it's logical that a higher temp would be more efficicent.

I wonder what would happen if you had a CAI, leave the intercooler uncovered, and only cover the radiater? Hot water + cold air = more efficient????