Engine/Transmission (1998.5 - 2002) thermostat temperature

[bighornram]

I just replaced my thermostat (fluctuating temps) with a cummins 3967195 which is what they gave me when I told them it was for a 2002. Immediately I noticed my temp guage is running lower. A search landed me at this link which identifies the thermostat as a 180*. Other searches seem to indicate the stock to be 190* supporting the apparent lower temp on my guage. What is the preferred operating temp for this engine? (most efficient) I'm wondering if 180 would be better for the summer months.

 

[klaybus]

I run a 180 degree thermostat year around in my 99. I believe the 99's came with a 180 & I have no heat issues in the winter & in the summer pulling our 5vr I have no issues either..... I have heard that the 02's do run a 190 degree thermostat though... .



Clay