Limited slip additive needed?

[pjm8047]

is a limited slip additive needed on a cone style sure grip? A 71 service manual/ owners manual says no but a 81 service manual says yes to the cone type. Also is the additive needed when using a full synthetic 75w90 ?

 

[dadsbee]

I'd never be putting full synthetic in a 50 year old design sure grip ! I put additive in all of them, right or wrong.

 

[RemCharger]

No clutches- no additives
Straight 80/90 for this guy

 

[pjm8047]

I guess I’m returning the 75w90 I bought and get the 8090

 

[pjm8047]

Returned the 75w90 synthetic and got this

 

[TN Mopar]

Returned the 75w90 synthetic and got this
View attachment 1173735

That's what I use
Don't forget the Additive
I use Mopar brand bought at the local dealer

 

[pjm8047]

That's what I use
Don't forget the Additive
I use Mopar brand bought at the local dealer

They want $20 a bottle for the mopar stuff. Ive read that lubegard limted slip additive works pretty good.
Lubegard 42851 Universal Slip Supplement, 4 fl. oz. https://www.amazon.com/dp/B01JRPAPLM/ref=cm_sw_r_cp_api_glt_fabc_MQSZQZYAE2100PRP3WW1

 

[33 IMP]

The motorcraft lsd lube is universally praised as the best. I dont know what it costs, ive got a locker, and a spool.
I would run the motorcraft stuff, even in a cone suregrip. Cant hurt. I would NEVER run synthetic gear lube!
Edit: found the genuine mopar stuff on amazon for $10.25. The motorcraft is $17 something. I would still buy the motorcraft.

 

[Juris426]

I just bought the Motorcraft lube on eBay for $9 a bottle and that included shipping. I put it in all sure grip units.

 

[forphorty]

Doctor Diff has the Motorcraft stuff https://www.doctordiff.com/friction-modifier.html