Dino juice or lab oil will be debated for the rest of time.
I dont use lab oil because it is expensive, does not give you any great benefit over the dino juice and costs twice as much.
I use Wal-Mart or Traveller (Tractor Supply Company) brand 85w-140 and change it once a year because I wade alot and I got water in my rear diff once and wasted $30 of Mobil 1 gear oil.
I am of the opinion that it is better to use a less expensive fluid and change it more often than to use a more expensive fluid and think you can just forget about it.

 

I like the rationale Spike, once again, thank you for the advice.