gear oil ?'s

[chevyridinhigh79]

i was wondering what weight gear oil i should run. my front axle is a dana 60 w/ a detroit tru trac and my rear axle is a 14bff w/ a detroit locker. my choices are 75w90, 75w140, or 85w140. i was told 75w90 would be sufficient but i wanted a second opinion. i was also told i need limited slip additive for the front axle because the tru trac is a clutch type posi, do i need it for the rear axle too?

 

[bigblock72]

75w90 is fine for both axles.

The tru trac is not a clutch posi, it's a gear type limited slip and does not require any additives.

 

[chevyridinhigh79]

hmm the guy im buying them from says in the add that its a detroit true trac limited slip. i always thought limited slip differentials were clutch type units. he was the one that told me i needed the addtitive.

 

[Hogback Fabrication]

hmm the guy im buying them from says in the add that its a detroit true trac limited slip. i always thought limited slip differentials were clutch type units. he was the one that told me i needed the addtitive.

If it is actually a Detroit tru-trac than it doesn't have clutches and hence does not need any limited slip additive. Be sure of what you have before you decide what fluid to put in (though adding the limited slip additive won't hurt anything).

As for the fluid, I generally use 80W-90. 75W-90 will work fine as well, any of the 140 weight oil is too heavy IMO.

 

[RaisedK5]

From the manual just so you feel better.

Lubrication​

The TrueTrac differential is designed to operate in those lubricants recommended by the vehicle/axle
manufacturer for conventional differentials.

More here http://www.eaton.com/ecm/groups/public/@pub/@eaton/@per/documents/content/ct_128482.pdf​