Quick update on this - the past few days, I've started it and used it in cold weather without using the block heater (as sort of an additional test). This morning was about 30 degrees when I got outside. The one concession I made was that I didn't hit the starter as soon as the wait-to-start light went out - I gave it an extra 10 or 15 seconds (my understanding is that regardless of the light, the glow plugs are still active for the first minute or two after you turn the ignition on).

It runs really well when it's cold now - it's like night and day. I feel like I can start it, drop it in gear, and go, and that's exactly what I did this morning, and it shifted perfectly. We've also noticed that it's much quieter and smoother. I'm amazed at the difference. It feels like a vehicle we can drive in the winter now, without preplanning (block heater); before it felt like a huge hassle.

Coolant level - it's hard to check in my driveway because it's off level. But I did check it while getting fuel last night, and it had already warmed up to the "full" level, which surprised me a bit. The gas station isn't more than a few miles from our house; I didn't expect the engine to be fully warm at that point. But, so far so good on coolant level. No signs of blowing out, although we haven't towed with it yet.

I think my wife is slightly annoyed I keep insisting on taking the truck places instead of the car with the seat heaters, or at least the car with fabric seats that is kept in the garage. (But she also gets that we just spent a buttload of money on it and we want to be sure the issues are fixed, so she hasn't complained.) We said we'll plan on putting seat heaters in it when it starts getting cool outside again, and I said we'll plan to upgrade the alternator and battery cable wiring then, too - realizing that two electric seat heaters would pull that much more power away from the alt that could be recharging the batteries.

Thanks for your help, everyone. This has definitely been educational for me.

 

I thought I'd update this thread. We traded in the truck last week on a new Ram 2500 with the Cummins. So far we love the new truck; we get to try its towing chops this weekend.

The F-250 was continuing to blow out coolant under load (towing our trailer up a hill, for example). Then I discovered a transmission fluid leak - either from the transmission cooler or the power steering cooler. We also knew one of the injectors was going bad. And it was doing other weird things - every now and then the HVAC panel would be completely blank when we started it, requiring a restart to get it working, the A/C was acting a little funny, like there was a vacuum leak messing with the blend door... and all this after we'd already dumped over $4K into it this year. Meanwhile, the underlying coolant-blowing-out issue continued, and I was afraid we would blow a head gasket.

In fact, we figured out that on average we've put over $3K into it each year since we bought it three years ago. We did some math and realized that our payment on the F-250 + the repair costs meant we could buy a new one for roughly the same price. Given all of the upcoming problems and what we'd put into it, we were both done with it. And we did love the Ram at the car show earlier this year. We didn't expect to be buying one, though.

The dealer had one on the lot, and they were ready to deal - it's an 8' bed with a fairly high level of interior luxury (seat heaters, nav system, steering wheel heater, etc.), something probably not a lot of people want, and the 2015s are due to roll in soon. So they gave us an excellent price on it, and they gave us a great trade in value on our F-250, so we couldn't be happier.

Thanks everyone for your help.