Anyone have problem with their posi chattering?

[BlacklandCamper]

Last time I opened a new bottle of Royal Purple, it smelled burnt. I don't care what anyone says about it being "more refined", NEW oil, synthetic, or dead dino, should NEVER smell burnt.

I use Castrol Tectron 75W-90. It contains the friction modifier already, and smells like new oil should. I have used it in several different trucks, with a range of different axles, used for different purposes. I have never had a problem.

[o6r1man]

Update: I drained the diff fluid and filled it back up with valvoline 80/90 and the ford additive. I drove it about 3 miles and it chattered a few times when I first set off, which I expected. I got to a big parking lot and did the 10 circles each way, I would say it is 99.5 better so far. I will get some more miles on it tomorrow and see how it does...

[outlaw 3454]

im telling you driving it in circles works!! it has for years.