I don't think any amount of friction modifier or gear oil is going to do squat to the LSD. Not enough to notice anyway. It is designed so that the a wheel has really gotta slip before it will engage. There is no magic additive that will make it work any different. That's just how it works. I can feel it kick in on wet boat ramps, and on steep inclines in the rain if I really mash the accelerator for a second or two. Under normal driving conditions I can't feel it...probably because it is not designed to work with just minor slippage. There is no additive that will all of a sudden change that fact or make the factory LSD feel like a locker or something.

FWIW, the X's LSD works exactly like every other LSD equipped 4x4 truck I have ever owned. I think it works just fine for it's intended purpose (but I agree that it's not all that great). You'd have to get a whole different LSD unit if you really expect to feel an improvement.