redtail2426

iTrader: (10)

Hey guys i have my rear all in the car and put about 100 miles on it,runs sweet too.Anyways i have the Trac loc posi unit in mine which is awesome and very streetable like the 10 bolt.What weight gear oil or brand do you guys recommend using with the trac loc posi unit.I will need to change it out at 500 miles.Right now it just has standard 80/90 weight oil with posi additive from the ford dealer.Thanks

MidwestChassis

iTrader: (5)

Synthetic can be used after break-in, but some diff unit manufacturers do not recommend using synthetic oils. As far as viscosity, for the break-in just any GL-5 rated or better 80/90 is fine. After the 500 mile if you do alot of highway driving or roadcourse use maybe a 85-140 type would be good. Drag only cars could get away with a thinner racing type lube. Any of our clutch type posi units will require a additive and we recommend the Ford OEM Friction Modifier. The Wavetrac, Truetrac, Detroit Locker, and spools do not require additives.

LS1-IROC

iTrader: (4)

Sounds about right, I have 80/90 in my Trac Loc posi and use the GM additive, works fine so far. I have just crossed over the 500 mile mark so I will be changing it out soon.