i have a torsen limited slip in my truck and am going to change the rear axle fluid. do I need to use a friction modifier, or not? I know the torsen is NOT a clutch driven unit, as are the stock ford trac-lok axles. I have the 75W-140 rear end fluid from motorcraft, as well as friction modifier, just not sure if I should use it. the parts counter guys told me they weren't sure if it needs it or not, but that it wouldn't hurt to put it in there.
2002 Ranger FX4
4.0L SOHC, 5R55E Auto, 4.10 8.8 Torsen, 31x10.5/15 BFG ATs