Just Go By Your Manual recommendations or do you not have one?
No. The visco lock is a sealed unit with its own super thick mystery fluid in it. What you run in the front diff will have no effect on it. I change the fluids in the xmr so frequently, because it's a bogger, that I just run the cheap stuff in the tranny and diffs with a little schaeffers moly lube. Engine gets Mobile 1 synthetic.yes 2013, is the front diff a special oil from can am ?
Personally I wouldn't waste your money on Am$oil. All 75w90 and 75w140 are full synthetic and anything you use will be more than sufficient. Mobil 1, Valvoline, etc. The key IMO is to change the fluids out on a regular basis as there is such a low volume in the diffs and gear box. One quart of 75w140 does about 2 oil changes in the diff and gear box. You could get 2+ changes out of the front diff with a quart of 75w90. I do mine annually, and I only average about 500 miles a year. The stuff comes out looking NASTY. I actually bottled up a sample from my gearbox to send to Blackstone because of all the wear metals in the oil