Rear diff fluid?

[cobia2017]

I recently changed my rear diff flood on M1008 14 bolt Detroit locker...is non synthetic 80-90 ok? Does it require friction modifier?
Thanks!

 

[TGP (IL)]

You will be fine.
I like 85/140 myself but that's me.
No modifier needed if it is a locker.
Tom

 

[cobia2017]

Ok thanks

 

[rustystud]

You will be fine.
I like 85/140 myself but that's me.
No modifier needed if it is a locker.
Tom

I also like the 85/140 though I use Synthetic. With all the heat the rear differentials experiences the 140w oil really makes a difference on the highway. No more screaming gears !

 

[biggerhammertx]

Friction Modifier is only needed for Positraction Limited Slip differentials. The Detroit Locker is mechanical and runs regular fluid without need for the special lubricant for the clutch packs that the Positraction has.

 

[cobia2017]

Thanks everyone