I agree. My heater is in the engine block, I use synthetic oil just for this reason too. And, I've never had an issue starting my Kubota B7800 in the extreme cold. I really believe that this combination is key!!
I was going through the same thing with my B7800! It would start then just quit. When I tried to restart, the engine would turn over but not start. The stop solenoid was not engaging which you'll hear when turning the key - it clicks and is very audible. The tractor would work fine for a...