Nice recoveries! Nothing like being able to pull yourself out when you get stuck. And your a lucky man, very few woman would even try to learn how to drive a skid steer, let alone do it.
I always wear mine, and my passengars wear theirs too or they can walk. I've been in two accidents in my life and the only reason I am here now is because of a seatbelt.
All things being equal, synthetics will always be better then conventional. However, if the truck was still under warranty, I would stick to what they recommend, then change later.
The 8.1L was a good engine indeed... it will be missed. Its a sad day when people lose their jobs, even sadder when an engine loses its place in the world.