Does anyone know what is the proper gear lube for Borg Warner 9 bolt rear ends.Can you use 80-90w oil.I know it is a cone type LSD so I would assume you do not need an additive to quiet the clutches like you would in the 10 bolt GM.Thanks.

 

I've used Mobil 1 synthetic 75/90w gear oil with the GM LSD additive with no problems.

 

Although conventional thinking says no additive is required in the 9 bolt posi, I've found that a friction modifier (I use a Ford product on advice from a fellow racer) quiets the rear considerably when maneuvering through parking lots and such. Admittedly, mine is a high mileage unit with lots of abuse (including a broken pinion).