Temp

[goeb34]

Driving around for roughly an hour about 40°F outside its below the 2nd hash about 160. So roughly 180ish is what im guessing. After sitting idle 15-20 minutes it goes back to where it normally is. It fluctuates some while driving. Is this a sign of a failing thermostat? 2014 sierra L86 coolant gets topped off every oil change. Only does it when it gets below 50°F (fall/winter time in Al).

[gone_fishing]

I replaced the thermostat on my Sierra last fall after starting to notice lower coolant temps. Brought it back up to closer to normal. It was a pretty easy replacement so it might be worth a try.