Since it was 10F this morning and going to be the same or colder tomorrow morning I figured I will get some statistics on how well a winter front works. I want to get mileage and time as to how long it takes to hit 190F. I will do a constant 55mph for these tests and be on the road within a minute of starting.

Today was without a winter front going straight into 20-30mph headwinds at 10F. Although synthetic oil seemed to not do anything at 20+F, you will notice that it cranks slower now that the conventional oil I am running starts to get really thick, you can even see how long it takes for it to get oil pressure. So synthetic does have it's place in the colder temps.

My EGT's were around 680F at 55mph when the engine was still under 130F, this proves how thick oil and cold surfaces make an engine have to really work. On the return trip with the engine at 190 and still at 55mph, the EGT was around 400F.

http-~~-//www.youtube.com/watch?v=vvVo4QMXX4Y

I took the thermostat out one time and mine did the same thing. Went 7 miles and just barely moved the gauge, it was still under 140 in 80F weather. I doubt your thermostat is stuck open though. How fast are you driving? I just went to town and back at 30-40mph (snow) and I just barely made it to 190 after 20 miles. Once the engine is warmed up, they don't seem to have much problem keeping warm as long you don't run the heater on full blast. I was on the interstate once and I don't have a fan on the engine and I pulled over for a bit waiting on someone and I didn't have the heater on to dissipate any heat. Just idling it was building heat (it hit 210F eventually), and it was only 10F out. Maintaining heat and getting it hot are 2 different things. I can pull a trailer and get it hot in a few miles or I can drive like I did today and the engine just doesn't work hard enough to get hot, plus having the heater on full blast takes heat away from the engine also. Let us know how you drive for those miles to work, it could be a big factor.

I fully understand the difference in maintaining and reaching the operating temp. So after work yesterday, I made an 8 mile trek down the highway to Gander Mtn (they've got this 10mm Glock I've been eyeing.) It was ~32*F, and the truck reached 190 about 2/3 way to Gander. It sat at 190 for a minute or so, maybe a slight bit past the 190 mark, then fell to approx 185 and held right in that range. It didn't get to 160 last week doing the same trip. This morning, it was 29*F. I didn't plug in last night, and did the same warm-up (truck went into high-idle) of about 3-4 minutes, before departing the driveway. Before reaching my work-20, I had hit and maintained 185-190*F. No winter front or radiator blocking of any sorts. Speed on the interstate yesterday was 65mph. This morning's work trek average 30-35mph over 6ish miles. Right now, my heater is ONLY full blast, until I replace the resistor box