WHAT DIFFERENTIAL FLUID?

[Russell James]

Originally Posted by kellyjrt

did you use it in the tranny and diff housing?

Yes, but it's different lube for each. RP Max gear 75w90 for the diff and RP Synchromax for the M6 trans. You need 1 qt for the diff, and 4 qts for the trans.

The Tremec tends to be a bit notchy when shifting, especially cold. I've owned tons of them, and they all do it. I've found the RP lube helps that notchyness feeling a bit.

[Moriartii]

I used Redline in my diff and have had no issues at all.
Cheers
K

[camaro52010]

Rear Axle (V8 Engine)
Rear Differential Fluid 75W-90 Limited Slip to GM Specification 9986226.
GM Part No. U.S. 89021677 and Friction Modifier 1052358,
in Canada 89021678 and Friction Modifier 992694.


Rear Axle
When to Check Lubricant
It is not necessary to regularly
check rear axle fluid unless you
suspect there is a leak or you hear
an unusual noise. A fluid loss could
indicate a problem. Have it inspected
and repaired.
How to Check Lubricant
A. Fill Plug Hole
B. Drain Plug Hole
To get an accurate reading, the
vehicle should be on a level surface.
If the level is below the bottom
of the filler plug hole, add some
lubricant. Add enough lubricant to
raise the level to the bottom of the
filler plug hole.


What to Use
For 218 mm rear drive module
(RDM) V6 manual, V8 automatic
and V8 manual:
To add lubricant when the level
is low, use 75W-90 LS gear oil
(GM Part No. US 89021677
and 1052358, in Canada
Part No. 89021678 and 992694)
meeting GM Specification 9986226.
To completely refill after draining,
see Recommended Fluids and
Lubricants on page 10-7. Then fill
to the bottom of the filler plug hole
with the Synthetic Gear Lubricant.
For 195 mm RDM V6 automatic:
To add lubricant when the level
is low, use 75W-90 gear Oil
(GM Part No. US 89021677,
in Canada Part No. 89021678)
meeting GM Specification 9986115.
To completely refill after draining,
see Recommended Fluids and
Lubricants on page 10-7. Then fill
to the bottom of the filler plug hole
with the Synthetic Gear Lubricant.

[ackeight]

Originally Posted by trott

Yes, no additives needed for Mobil 1.

I put about 3 oz of the friction modifier in with the Mobil 1 because is says something along the lines if you drive it harsh you should still add it.

[kellyjrt]

great information from everyone, I hope this thread will help other with their decisions when that time comes..I appreciate the input on RP, Mobil 1 and factory OEM fluids..never hurts to get a good variety of opinions...but for the most part if I go with any of these suggestions I'm good to go.

[ZED SLED]

Originally Posted by ackeight

I put about 3 oz of the friction modifier in with the Mobil 1 because is says something along the lines if you drive it harsh you should still add it.

I had the dealer do mine @5500 miles so there would be a record of it, but provided my own Mobil1 75W90, along with FM because I have read on here where several people had some whining and groaning noises even after doing figure8s and went away when they added the FM. No issues, no sounds, I did the figure 8s anyway, then busted off 3 hot laps at Watkins Glen. Everything is still good.

[ricks dream car]

Originally Posted by kellyjrt

I WOULD LIKE TO KNOW IF ANYONE HAS CHANGED OUT THEIR DIFF FLUID ON EITHER A V8 OR V6 YET? AND IF SO DID YOU USE FACTORY WITH THE FRICTION MODIFER OR GO WITH SOMETHING ELSE? MOBIL SAYS THAT THEIR GEAR OIL CAN OR SHOULD NOT BE USED FOR THE REAR DIFF. ANY SOLID INFORMATION WOULD BE APPRECIATED.

I CHANGED MINE AT 7900 MILES THE DIFF WAS MAKING NOISE WHEN I BACKED WHILE TURNING. THE FLUID WAS NASTY AND BURNT. THERE WERE ALOT OF METAL SHAVINGS ALSO. I USED MOBILE ONE FULL SYNTHETIC LS 75/90. WITH THIS FLUID THERE WAS NO NEED TO ADD THE FRICTION MODIFIER. BECAUSE THE OIL THAT WAS IN IT WAS SO NASTY, I DID NOT PUT THE FACTORY FLUID BACK IN IT

[ricks dream car]

Originally Posted by kellyjrt

so you used Mobil 1 75w-90 gear lube in the differential without adding the friction modifer?

I DI IN MINE. THE NOISE WAS GONE IMMEDIATELY!!!! I COULD TEL AS I WAS BACKING IT OUT OF THE SHOP. IT WAS A HUGE DIFFERENCE.

[pennor]

Change the differential fluid??????????

Why I never heard of such a thing!

I have a 37 year old Corvette with the factory differential fluid in it. I think they were still using whale oil for a friction modifier in the Posi-Track system back then. It has 127,000 miles on it. It still works fine and that differential has given me great service through racing, daily driving and long trips for almost 4 decades. So why in the world would someone take a brand new car and change the differential fluid?

Now I'm going to sit back and wait for an answer that makes sense to me.

[Ron66Vette&10SS]

Owner's Manual recommends to change the diff fluid after the first 1,500 miles if the car is to be used for racing or performance driving (or something to that effect).

[ducq]

after reading many posts I went and changed my differential and transmission fluid, it was real easy to do. I noticed a huge difference in drive train noise and my shifts are just straight out smoother all around. Just like someone else posted on another thread, on cold starts my gear changes are seriously like butter!

[squatin0n18s]

i noticed in my manual that it doesnt say to use the friction modifier on the A6 V6. Any ideas why not? Can i just use the mobil 1 and be done with it?

[RiCorvette]

A bit of an aside;
I used Royal Purple for the Tranny and Diff and inevitably got some on my coveralls.

I'm washing them for the third time now (Tide) but the smell is still pretty strong and me Missus and urchins are complaining.

Any suggestions to help get rid of the smell? I'm gonna try bleach in the next run through.

[jmaryt]

Originally Posted by squatin0n18s

i noticed in my manual that it doesnt say to use the friction modifier on the A6 V6. Any ideas why not? Can i just use the mobil 1 and be done with it?

the reason is your auto does NOT have 'posi-traction"..you don't require the modifier!..modifier is for limited slip differentials!