Getting ready to change my radiator fluid and noticed here lately that my temp gauge is fluctuating alittle. It has always read just below and to the left of 200 degrees. All of a sudden its now to the right and just over 200, but when I get on the highway it goes back down. Only concerns me cause its never seen over 200...even last year in 100 degree weather. Brings me to think I should swap out the thermostat when I change the fluid. Any particular brands anyone using or should I just pop into auto zone and pic one up ? Oh yeah and what degree is it ---190 ? Thanks in advance

 

When you do the coolant change out go ahead and replace the thermostat also. I would suggest/recommend getting one from a Cummins authorized parts place than from a auto parts place. I believe they use a 195*F thermostat.

Tony