80w90 Gear oil in the RearDiff.
15w40 Rotella in the Engine and Purlator PL14612 or PL14610 Wal Mart
Travlers Premium Universal Trans/Hydrualic Flud from Tractor Supply for the Front Diff, Tranny and Transfercase.
You will find as many other choices on here as you have fingers! I do however agree with the inevitable response, that if your under warranty, stay with what Polaris tells you to use, unless you want to become your own Warranty!!!!!!!!!!
I don't have a Tractor supply near me, but Champion Premium 4000 is GL4 and is same as Mobil 424 which is what the gear boxes are filled with from Hillard and Spicer. Any 75-90 or 80-90 GL5 in the back
Synthetic Rotella 15/40w. I did pick up a Bosch 3323 filter instead of the PL14610. Felt a syn oil and better filter was money well spent for a push rod engine that spends a lot of time around 4,000rpm's+
But.....It only takes 2 qts for the engine, 2 qts for the tranny and transfer case, and 6-7 oz for the front, @ $10-12 a qt is the savings that big of a deal. Probably not, but the other fluids are closer to me.