Yes, I overheated the XJ on the way home from work Tuesday night at 11:15PM with temps running around -8 degrees!
And it happened just 5 miles from work with 35 miles to go to get home! 
Roads were just a sheet of ice about 1-1/2" thick and I was only running about 20 - 25 mph. I was beside the road with the hood up looking at all the steam and overflow from the radiator, freezing my booty off when a guy pulled up in a nice diesel 4x4 truck and asked if he could help! 
We got the XJ to start and he escorted/followed/led me to his house in Jasper, MI. We pulled the Jeep into his pole barn and let it cool off while he invited me in to warm up and gave me a beer! 
Went back out and he pulled antifreeze off his shelf, helped me add it, checked my oil for foam (didn't find any, thank god! 
) added a quart of oil to the engine for me, checked my tranny fluid, got it started again and let it run for a while to see what happened and why it may have overheated, checked for leaks. Didn't really figure anything out other than maybe the thermostat stuck or something? Maybe I didn't have enough antifreeze/ too much straight water? 
Anyway it ran for a while and didn't seem to be overheating again, so I offered him the $10 
I had in my wallet and he wouldn't take a dime!!! I didn't notice it on the way in but on the way out I saw his "other" truck. Nice BIG old blazer with 42's, big old bogger! 
Thank God for good samaritans and fellow wheelers!!!!!!!!!! I'll have to warm it up and check the oil/antifreeze again in the morning to make sure I didn't blow a head gasket or something. The gauge was pegged above 280 and blew out a LOT of steam and antifreeze. We added almost 3 gallons of antifreeze mixture that he pulled off of his shelf. Again, that stuff's not cheap, but he wouldn't let me pay him for it at all!!
