differential fluid

[Aaron4TAMU]

Ditch the crush sleeve for a Ratech spacer & shims, then it won't deflect into never-never land again. Of course, then something else might give...

I found the part #4111 for 10 bolt 7.5 for $18.99. This a decent price?

[fastTa]

When I first bought my 97 WS6 one of the first thing I did was change most of the fluids. One of those being the the differential lubricant. I bought the car from the original owner and he said that he had changed the diff lube only once and just used the GM non-synthetic.

Well there is a little back road a few miles from my house with nothing but corn fields around you. There are a few 90 degree turns that I use to have a little fun with if you know what I mean. I could give the car WOT just after the apex of the turn and throttle steer out of it with the power being distibuted pretty evenly to both wheels.

Well immediately after changing the rear diff lube to Mobil 1 Synthetic, the car was experiencing a MAJOR drivetrain slippage problem when I was playing in the same 90 degree turns. I wasn't quite sure if it was the tranny or the rear at first so we thought we would use the process of elimination and replace the rear diff lube with the standard GM stuff. Presto! The slippage problem vanished.

Could it be different brands? Could it be only isolated cases? I don't know. But I do know that the synthetic lube in my rear caused major posi clutch slippage. BTW, yes I did add the limited slip additive with the synthetic.

This is definitely an interesting topic!

[Kevin - Blown 95 TA]

My posi has lasted 135K miles with synthetics. When the pinion seal went and the bearing shortly after, I upgraded the gears to 3.73s and still didn't need to touch the posi unit itself. It's had mucho quarter mile passes with sticky tires and no problems at all.

Joe, do you have the cone style posi or actual clutches & springs like in an Eaton?

[fastTa]

The all-gear drive differentials like the zexel-torsen probably wouldn't be affected by this as they have no clutches. I was looking in some my Strange and Mark Williams literature and they both say they DO NOT recommend synthetics in the Eatons. I'm not sure what the difference is in the Eatons and the Auburns, but I would imagine they are similar for the most part.

[Aaron4TAMU]

The all-gear drive differentials like the zexel-torsen probably wouldn't be affected by this as they have no clutches. I was looking in some my Strange and Mark Williams literature and they both say they DO NOT recommend synthetics in the Eatons. I'm not sure what the difference is in the Eatons and the Auburns, but I would imagine they are similar for the most part.

AHHH, it may be my Eaton posi that had that warning. My memory is so bad.

[Joe 1320]

Joe, do you have the cone style posi or actual clutches & springs like in an Eaton?

It's an Eaton. I am really curious to the effects as well. I've seen some coflicting recommendations also. At first I used GM synthetic, but then switched to mobil 1.