My new Kubota would not start in the extreme low temps this winter. It would start fine down to about 10 degrees, but colder temps caused it to not start. The battery would have enough juice to glow the glow plugs for 3-5 seconds, but if the engine did not spin fast enough in the first few seconds to catch and start, the battery would be too weak to try again.
0 and below temps are pretty extreme, and I did have the factory fill oil in the crankcase, so when I did my 50 hr service, in went Rotella T6. I'm hoping that will get better next year (might go with a stronger battery too).
Since I'm averaging about 50-60 hrs per year, annual oil changes will include synthetics. Also its the same oil I use in my dumptruck, so its nice to stock it up when on sale and leave it on the shelf.
Over the years I have become fond of stocking common oils that will work for many applications and OEM filters.