Rear differential noise/lock up??

[pauld]

I decided to change the rear differential oil. 180k on the car and no clue when it was last changed. I don't remember hearing anything before. I used Lucas oil. Now after warmed up on tight slow turns I hear moaning and almost feel like slip is not slipping as good as it should.
I just replaced the front end and I am NOT looking foward to replacing the rear. Anyone have any experience with these sounds?? Thanks

 

[jrt67ss350]

Does your car have a limited slip rear end in it? Did the differential oil that you put in have limited slip additive in it? If you have a limited slip differential and don't put in oil that has a limited slip additive in it, it'll cause the exact problems you are experiencing. If you have a limited slip rear end, and your oil wasn't for limited slip differentials, all you need to do is go get a bottle of limited slip additive and put it in there - should fix ya right up.

 

[pauld]

I did not verify any numbers but both wheels spin foward when on stands, so I thought that means it is limited slip. The oil said it was for limited slip and any gear application. 80-90W heavy dudy. I'll get the numbers when it stops raining to verify.
Thanks Justin

 

[jrt67ss350]

Well, if both wheels spin forward when both of them are off the ground, you've got a limited slip differential. That's weird about the oil if it said that it was for limited slip differentials. I still think that's what it is though. I don't have a limited slip rear end in my BMW - the only experience I have with them is from GM muscle cars. Maybe someone else on the board here can give more info about the additives that are needed for BMW rear ends - maybe they need something special that isn't in "normal" limited slip-ready oil??