Dang! That's a great point! I hadn't thought about that. And actually, when I lived up there, I owned an '85 F250 with the 6.9L International diesel motor in it. It too had block heaters, but of course, no DEF, no emissions of any kind, and perhaps more importantly, I lived in south Anchorage, right on the water, so it didn't get quite as cold there.Should hunt for members up there to see what happens to them.
But it would be very interesting to learn from some present-day Alaska owners of Powerstrokes, just what they experience with their DEF systems in winter. I wouldn't think it could be too good, but then, who knows?