1995 Z28 Rear Diff Lube
08-07-2013, 09:00 PM
#1
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1995 Z28 Rear Diff Lube Hello-
Being that I have to replace a set of rusted rear rotors on my new-to-me 1995 Z28, I figure I'd change the rear diff lube at the same time. Doing so will also let me see what gears I really have.
The car is stone cold stock and had 47,400 miles...no joke.
I would normally assume a GM rear has an Eaton limited slip in it unless a Torsen was optioned, but I hear that Auburn supplied the differential for the 1993-1997 cars. Which is right?
Does anyone have suggestions as to the right diff lube for it? Normally I would put 75W-90 Synthetic (Valvoline or Mobil 1) in it with LSD additive, but I hear synthetic may be bad for the Auburn cone diffs.
Any guidance would be most welcome.
Thanks-
Dave
Being that I have to replace a set of rusted rear rotors on my new-to-me 1995 Z28, I figure I'd change the rear diff lube at the same time. Doing so will also let me see what gears I really have.
The car is stone cold stock and had 47,400 miles...no joke.
I would normally assume a GM rear has an Eaton limited slip in it unless a Torsen was optioned, but I hear that Auburn supplied the differential for the 1993-1997 cars. Which is right?
Does anyone have suggestions as to the right diff lube for it? Normally I would put 75W-90 Synthetic (Valvoline or Mobil 1) in it with LSD additive, but I hear synthetic may be bad for the Auburn cone diffs.
Any guidance would be most welcome.
Thanks-
Dave
08-08-2013, 07:12 AM
#2
I'm the original owner of a '96 Z-28, without the Torsen, since as far as I know, the Torsen was only available as an option with the Z-28 SS package.
I changed the gear lube when the car was about a year old, to get all the grey, grimy, moly break-in lube out of it, and then changed it again a year later, to really clean out any residual moly. The third year, I put Valvoline Syn gear lube in the car, and that's what's been in there ever since, no problems.
Having said that, I was talking to a tech rep from one of the oil companies around 1997-98, and mentioned to him that I had recently (at the time) put Syn gear lube in the rear axle of my wife's Caprice LTZ. He asked me how many miles were on the car at the time, and I said 50,000. His reply was, "I hope you don't have any leakage issues", and explained that over extended periods of time, the seals in the rear end will "acclimate" to the characteristics of the oil used, and changing to a Syn oil, with different properties could negatively affect the seals.
I'm only mentioning this as a precaution, as your car, obviously, has probably had the same oil in it for quite some time.
I changed the gear lube when the car was about a year old, to get all the grey, grimy, moly break-in lube out of it, and then changed it again a year later, to really clean out any residual moly. The third year, I put Valvoline Syn gear lube in the car, and that's what's been in there ever since, no problems.
Having said that, I was talking to a tech rep from one of the oil companies around 1997-98, and mentioned to him that I had recently (at the time) put Syn gear lube in the rear axle of my wife's Caprice LTZ. He asked me how many miles were on the car at the time, and I said 50,000. His reply was, "I hope you don't have any leakage issues", and explained that over extended periods of time, the seals in the rear end will "acclimate" to the characteristics of the oil used, and changing to a Syn oil, with different properties could negatively affect the seals.
I'm only mentioning this as a precaution, as your car, obviously, has probably had the same oil in it for quite some time.
08-08-2013, 08:30 AM
#3
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Torsens were something like a thousand dollar option in the LT1 SS. They became standard for '98 and up ls1's. Something like that anyway.
I've had Torsen, which I cracked in half, replaced with an Auburn, then went w/ a 12-bolt and have an Eaton HD. I've always used 75 or 80w 90 gear oil and used limited slip additive (except for the Torsen anyway).
I've had Torsen, which I cracked in half, replaced with an Auburn, then went w/ a 12-bolt and have an Eaton HD. I've always used 75 or 80w 90 gear oil and used limited slip additive (except for the Torsen anyway).
