Mobil 1 full synthetic limited slip gear oil WTF?

[cs_88]

So it's been about 500 miles or so since I installed the new gears and rebuilt the stock limited slip in the ol' nine inch and I'm thinkin' it's a good time to change the oil.
I picked up three quarts of Mobile 1 synthetic limited slip gear oil thinking it would keep everything in the rear end happy.
Well, I guess not. It seems now I've developed some nasty clutch chatter. WTF?

Looks like I'll be adding a friction modifier after all.

Lesson learned.

 

[blazinchuck]

i just rebuilt my trac lock...and im using stock gear oil(whatever it is) but i didnt use the friction additive...i wanted a tight posi. so far its been perfect. with a 5sp i dont even know i have a posi until i make it thru the mud or rocks and realize i had great traction

i even looked to make sure the gear oil didnt say it was "safe" for limited slips or posi...most fluids have fric. additive in them.

 

[73azbronco]

you may want to check the manufactures recommendation on the clutch materials. Although, I've never had issue with mobile 1 syn for posi rear ends.

 

[blubuckaroo]

The synthetic oil is part of the problem. It's too slick for the clutches without the friction modifier. Get the stuff from the Ford dealer. It will work fine with your synthetic oil.