7.5" 10 bolt rear torsen fluid question.

**2002ssslp** · 05-29-2012, 06:28 AM

OK, I had the funds for a Moser 9" for my 2002 SS. I was about a week away from ordering it when we got hit by the perfect storm. Kid's Tuition bills, Homeowners insurance and wife's medical bills hit the same week as mortgage. Oh Well, maybe next year. I have 31k on my Ss and do not want to put any money into the 10 bolt so I decided to put a TA girdle cover on the rear when I change my fluid next weekend. 159.00 plus fluid is ok since I can resell the girdle when the rear goes. My question is what is the best fluid to use with a Zexel Torsen diff. ? I would like to get the summer racing season out of the rear and swap it out over the winter. Thanks for the help. BTW, I run stock Goodyear F1 GS that came with the car.

**INMY01TA** · 05-29-2012, 05:14 PM

I've always used any 80/90 conventional gear oil + 1 bottle GM limited slip additive.

**cpop98ws6** · 05-29-2012, 05:19 PM

^^ That is what I ran when I had the 10 bolt in the car.

**INMY01TA** · 05-29-2012, 05:39 PM

Originally Posted by cpop98ws6

^^ That is what I ran when I had the 10 bolt in the car.

That's all I use in my 12 bolt too.

**cpop98ws6** · 05-29-2012, 05:45 PM

Just straight 80/90 in my S60, no need for the additive with the Detroit Truetrac

**pajeff02** · 05-29-2012, 06:01 PM

Tried to swap my Valvoline out for Amsoil a few weeks ago and the damn drain plug is seized in the aluminum cover... again!

**Too Fast** · 05-29-2012, 06:03 PM

^^^but for the F-bodies, it was synthetic 75w90 for the V8 cars, and possibly the V6, as specified in the owners manual. I've never read anything absolute about having to use the additive for Torsens, but it won't hurt any differential it to use it if it's not needed. That's what I've always run in my Torsen equipped car, with a TA girdle and welded axle tubes. 113k and no noise or problems whatsoever, lots of trips at the drag strip too. I've had many 2.0x 60 ft times, some 1.9x, but then again I've never ran slicks or ET streets either.

**pajeff02** · 05-29-2012, 06:11 PM

Quote straight from Torsen's site:

Is it true that the Torsen unit in the production Camaro needs the GM modifier added?

GM issued a technical bulletin adding modifier to the rear axle oil. This was done to quiet what we call a "Rusty Screw" noise that we heard in a very small percentage of vehicles. This does not happen in all cases, however to address owner's concerns we asked that the modifier be used in all instances to insure that the driver would not get this noise. When replacing the fluid it is at the owner's discretion whether or not to add the modifier. Elimination of the modifier does not affect durability of the differential.

**INMY01TA** · 05-29-2012, 06:17 PM

If I remember correctly I tried using the Redline synthetic shockproof gear oil in my 10 bolt a long time ago and started getting one wheel peels.

**pajeff02** · 05-30-2012, 02:42 AM

I run Redline in our Corvette rear and have had no issues with the posi. Seems that the synthetic stuff will mostly work without an additive, but if you experience any chatter the fix is to dump some in.

**cruzincamaro** · 07-26-2012, 11:42 PM

I had a case of the "rusty screw", replaced the RP oil with syn racing diff oil and additive. Noise is still there, sometimes. 41K on the odo. Do I have a problem? I also read a lot about going to 12 bolts or 9" etc. The $ is high and as I was reminded, the shipping might really bite. So, I also read about just replacing the diff with an aftermarket set up. Any recommendations? The shipping to here might be less painful for only a diff. Plus, I don't race so a 12 or 9 might be overkill for me..Yes/No?? Thanks!!

**Too Fast** · 07-27-2012, 02:12 AM

The rusty screw is only a minor noise issue, from what I've gathered. It doesn't mean you're having catastrophic failure, so unless you just have money to spend, I wouldn't worry about it. You can always do a drain and refill again, are you using synthetic diff oil like the owner's manual wants?

**cruzincamaro** · 07-27-2012, 10:00 AM

Originally Posted by Too Fast

The rusty screw is only a minor noise issue, from what I've gathered. It doesn't mean you're having catastrophic failure, so unless you just have money to spend, I wouldn't worry about it. You can always do a drain and refill again, are you using synthetic diff oil like the owner's manual wants?

Yes, it's a synthetic diff oil that a buddy uses for his race car, plus the additive. I was hoping that it was just an annoyance. I've even read about a guy double-dosing the additive with good results. I guess it wouldn't hurt. Thanks for the reply