Odd experience and question regarding PML diff cover...

[TIsTAN]

I thought I'd just throw this out and see what type of responses I get. After having changed to the aftermarket cover using synthetic Mobil1 75w140 (just about 3 qts), I feel a lag when accelerating. It's as if the parking brakes are on slightly or if there is a hole in the exhaust...wants to go but not as readily as before until you really gas it. Is anyone else with this cover having similar experiences? My bro said something similar to me when he had to drive my truck (he was unaware of my experience). A buddy said I might need a friction additive but I don't recall anything from the many posts I read. Just a normal difference having changed from 75w90? Otherwise, it's not leaking and the truck drove normally before the change. Thanks!

edit - This was the first rear diff change at 17K miles a lil more than a month ago. Truck is lifted (8" CST) with 35s and I do not tow.

[Herbpov]

No change in mine. I went from stock 80w-90 to Valvoline SynPower full synthetic 75w-140 Limited Slip Extreme High/Low Temp Protection.