Diff. Fluid

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Apr 6, 2007 | 10:16 PM

Suber

Thread Starter

Elder User

Joined: Mar 2007

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From: Albuquerque

Diff. Fluid

Hey all, I am about to change my gearbox and front/rear diff fluids and would seek some feedback. I am not sold on synthetics but am open to ideas. I have mostly stuck with Valvoline in the past. Fire away!!

Apr 6, 2007 | 11:29 PM

RubberDuck

Logistics Pro

Joined: Jul 2001

Posts: 4,137

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From: Marble Falls, Texas

Amsoil ATF in the 5speed or Auto Amsoil 75w-140 in the diffs and don't forget about the limited slip additive. That's what I run and love it. Alot of the guys on here like the Royal Purple which also is excellent, or Redline which is very good as well. Basicly it comes down to personal preference.

Apr 7, 2007 | 02:52 AM

audimaster

Senior User

Joined: Sep 2006

Posts: 161

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From: Indiana

I've been searching much on this topic

the 75-140 weight or 75-90 weight, and the synthetic vs. dino. I finally just went with 75-90 synthetic for the best of both worlds.

Apr 7, 2007 | 10:44 AM

Suber

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Joined: Mar 2007

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From: Albuquerque

I am wondering if I have a posi rear-end, or slip on my 1-ton. I am not sure. I am told you have to put an additive in if it is a posi-trac rear-end.

Apr 7, 2007 | 10:56 AM

Cuda_jim

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Joined: Oct 2003

Posts: 5,903

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From: MICHIGAN

Lift both rear wheels off the ground, put the tranny in 'N', spin one tire, if the other spins in the same direction you have Posi, If it goes in the opposite direction, ot doesn't move you have an open diff.

75-140 syn has the posi additive in it but you still need to add 4-8 oz's. IMO.

Check the tags on the outside of the diff cover. Post the #'s here for de-coding.