Rear Differential Lube Change
– 1.69 Quarts of M1 Synthetic Gear Oil (GM equivalent
12378261) SEA 75W-90 (Z06 3.42’s, other gears may vary slightly)
oz. of limited slip additive (EQUA TORQUE) or GM part #1052358
– A big
‘ole Hex Key, like 1/4″ I think it was ..
– Some rags and a fluid oil
pump ($5 at pep boys, very useful)
the car up or drive it on some ramps, so you can get under the rear axles.
Then support it, so it doesn’t kill you (:smash:). Next, find the drain
plug on the bottom of the gear box, which there are two of, so don’t get
confused … one is actually on the side, it’s the FILL Plug !
Safey is first
actually used ramps on the rear, but you get the picture, right
The one from the back, is the FILL (It has a little tag
attached to it) pointing rearward and facing
between the rear swaybar and leaf spring … DO NOT GO TO YOUR
TRANSMISSION, YOU’VE GONE TOO FAR.
This big thing is your
… so let it all
18.5K miles, this is what the old gear lube looked like
In my case, there were no significant “metal” particles or
anything like that – but some have reported a couple of lose gears and
ball bearings (just kidding) – in their gear box, especially all you 3.73
and 3.90/4.11 racers ! 😆
Now … retighten bottom plug to 26
lbs-ft. & pump in 1.69 (about 1 and 3/4, little less — quarts of the new
stuff – as such, using the
In the process, you will add ANOTHER 4 ouches of limited slip diff
fluid, to top it off until little begins to pour out, or to top of rear
fill plug! Don’t over fill it !
Retighten, this second bolt to 26
lb.ft – and drive normal, NO WOT – until 300 miles have passed. Send me
email, if you got more questions. Total time to do this is approx 30-45
mins, if you’re maticulous. Total cost was $30 vs. $140 @ dealer.