Help! New thermostat running at 170

[Lazy-Boy]

Is this right? I got a 2001 model and have been running at 185 degrees with the stock thermostat. Well the truck is two years old and the engine temps starting fluctuating a little. Bounces from 180 – 190 on the stock gauge. I thought I’d change the thermostat just in case. Got part # 3954194 from Cummins Southern Plains in Dallas. Now it’s bouncing from 165 to 175.

Is that to cold? Maybe I got the wrong part number.

 

[Lazy-Boy]

Correct part numbers for thermostat

OK, I did some more digging and it looks like I got the 180 degree thermostat and the 190 is a different part number. And maybe my stock gauge is reading a little lower then actual.

2000 - 2002 3954194(180 deg. ) & 3937171(190 deg. )



So let me change my question…

What’s better, to run at 180 or 190? Why?



Thanks in advance



Steve

 

[Bigsaint]

I'm not sure that 10 degrees really matter much. Mine's always right at 190 degrees at running temp. , according to the DC gauge.