If you use the balanced flow thermostats (extra duty Robertshaw, yes what Kennedy sells) then you'll be fine with either 180 or 195. The 195 AC-Delco is identical to the HD Robertshaw stat, the AC is a great stat (the one for the 6.5 dual application, not gasser application).
So it basically boils down to:
Running empty in hot climate:
195 (more efficient running engine)
Running empty or pulling light in cold climate
Pulling in Hot climate. or Pulling large loads in cold climate:
I'm in Texas, so I run the 180, but it ain't too warm in the winter...
I would run the AC 195's. KENNEDY even has a right up on it in his ad for the upgrade saying he runs the 195's, but carrys the 180's because customers request them. Many people run there diesels to cool and it hinders them. Most diesel's need to run around the 200-210 range to reach peak efficiency and maximum burn and power.
I live in Sacramento CA area and we get 100-110 degrees and I run the 195 AC Delco thermostats towing 7000 lbs.. All a 180 thermostat is going to do is maybe take a little longer to overheat if you are having an issue.
I run 180's for the simple fact that on hot summer days the cooling process starts early and I don't have the complete upgrade on mine yet. Running 180's will not make you truck only run @ 180 but will let coolant flow sooner. I believe some run them split and that would be a good combo too IMO. When I finish my upgrade I will split mine up I think.
A forum community dedicated to Chevrolet and GMC diesel truck owners and enthusiasts. Come join the discussion about duramax engines, performance, builds, modifications, classifieds, troubleshooting, maintenance, and more!