What type of differential fluid is recommended for this cone type clutch, car is all original with 30k miles & no problems with differential, just wanted to change the fluid after 30 years to preserve the differential. GM fluid part#1050010 is no longer available from GM. Owners manual says additives are not recommended! I'm getting mixed opinions on oil type & to add additive or not?

I filled mine with something I got from Summit racing -

www.summitracing.com/parts/bpo-023-7729.

Supposedly retro formula for vintage cars. No additive.

edit: Oops - I see it's unavailable

I just put regular gear oil in mine, no additive, not sure how that will effect it though. Doesn't chatter or anything and when I did a 5,000 change there wasn't an excess of flake in it. Mine was bottomed out and I ground the lip down in the carrier and the edges of the cones, and shimmed the spiders, hoping to get a little more life out of it. I just plan on changing the oil more frequently. I put the TA performance girdle on it and it has the drain and fill ports, so doing ~10,000 change intervals isn't going to be a big deal for me.
If I kill it I am just going to buy one of the helical carriers.

This looks better

http://www.jegs.com/i/Driven-Racing-...04530/10002/-1

Much better bottle, too.

9 bolts are not your typical rear diff. They don't work with everything well.

They seem to work best with:

Torco AFM0050JE Type F Limited-Slip Additive for Ford - 4oz
Torco A248514CE 85W-140 Racing Gear Oil

150k on my rear end. Previous owner had some nasty old fluid in there. Made noise after freeway runs. Swapped to the Torco fluids and it's quiet as can be, locks up great when it's supposed to, etc.

Further reading: https://www.thirdgen.org/forums/faq-...now-about.html

^^^^
what he said .. worked good for me

Book calls for 1.8 quarts of 75W90, (GM 1050010) & NO additive. Pick what-ever brand you prefer..... as long as it's fresh your rear end will thank you !

Book may call for that but I'd run the Torco stuff on 9 bolts.

All good,

I'm fairly certain that a 30 Y/O 30K mile car doesn't require Racing gear oil. Since this is the "history" section I didn't recommend any brand of fluid,..... just posted what the factory shop manual specified * every shop manual I've got that covers the BW rear end says the same thing:


GM 1050010 (75W90) and NO additive.

I have the LB9 axle & the owners manual doesn�t specify oil viscosity & weight just a number fir the 9 bolt unit. Lol Thanks for the advice. I�ll look @ my 87 Camaro Factory Shop Manual too!

I go by what GM says - NO ADDITIVE. I dont think it matters a whole lot in the long run, though.

Note the auburn posis and the 9 bolt posis use the same basic mechanism - cones. So even though the 9 bolt is constructed slightly differently, the unique posi parts that are rubbing are the same for both. I know GM went back and forth on the additive over the years, so that adds a layer of uncertainty to it.

Thanks for the advice! I'm
Leading towards no additive!

Also I contacted 9 Bolt in Australia, this is what they suggested for the
9 bolt with cone clutches.

Hi Horacio,

I like to run 85/140w gear oil. You will need the friction modifier to stop chatter. Some oils will include a friction modifier (check the label). You could also run 80/140 w synthetic.

Cheers, Glenn
9Bolt.com

So after some research I have found a direct replacement for GM part#1050010 differential gear oil for the BorgWarner 9 bolt differential. Red Line 57904 (75W90) Synthetic Gear Oil

I think you are overthinking it. I just put in el-cheapo gear oil from Walmart. No chatter and I am not seeing an excess of metal flake in the oil.

So, these diffs aren't really expected to get too long a life out of them. Coupled with people not changing the fluid nearly enough, they wear out fast. Mine had copious amounts of flake when I took it apart, and the housing was actually galled from the metal wear built up between the cones. For this type of diff, I think changing it more frequently is more imperative than what type of fluid you should put in. I even epoxied an old hard drive magnet to the bottom of my housing to try to control all the metal that comes off.

I realize this has not been touched on in a while, but for the record...

1989 Pontiac Firebird Service Manual S-8910-F at p. 0B-8 Maintenance and Lubrication, "Limited slip differential rear axle - All models require GM part no. 1052358 lubricant additive."

Resource: https://www.gmpartsgiant.com/parts/gm-addt-1052358.html ; GM 1052358 Additive, Limited Slip Axle Lubricant 4Oz.

1988 Pontiac Firebird Service Manual (Thanks Uncle Phox) indicates the following for limited-slip differential rear axles:


"For Camaro only - Use SAE 80W190 GL-5+ Hypold Oil (GM Part No 1050010), if equipped
w/5.7L (L98) Engine or 5.0L (LB9) engine w/5speed manual transmission and disc brakes
All other applications - Use SAE 80W or SAE 80W-90 GL-5 Gear Lubricant(GM Part No
1052271)."