I'll net it out:

If you you use somthing other than the factory recommendation, one of three things will happen:

1) It will work great
2) it will grab, bump, and chatter
3) the limited-slip effectiveness will be reduced

If you follow the factory recommendation one of one things will happen:

1) It will work great

Also, the Viper arguement doesn't work. If the engineers designed the carrier for this synthetic from Chrysler:

Synthetic Gear & Axle
Lubricant SAE 75W-140
High-performance synthetic
GL-5 gear lube. Also highly
recommended for LX body rear
axle. Recommended for trailer
tow and heavy-duty, high-load
vehicles.
1 Quart (32 Oz.) Bottle
MSQ: 12 Bottles
Part No. 04874469
MS-8985

...then that's what you should you use for the LX axle. Like the Corvette enigineers, I'm sure the Chrysler (Viper, engineers) know what they're doing. Also, are you sure the Viper used limited-slip diffs? Thought they used Torque-Lock or Hydro-Lock. Whichever, I'm sure the clutches or clutching or locking mechanisms were designed for use with syns.

Also, Aurora40, I don't know what's so hard to understand about Dana's recommendation in the link above. Below are direct quotes:

"Some otherwise good lubricants do not preclude chatter or buming...some vehicle manufacturers find it necessary to specify a lubricant and a special lubricant additive for use with limited-slip differentials...Check vehicle manufacturerer's recommnedation".

Again, read engineers' recommendations calling for petro lubes Dana, Eaton and Auburn (three giants in the industry) for their limited-slip diffs:

http://www2.dana.com/pdf/5323.pdf

http://www.eaton.com/EatonCom/Produc.../FAQ/CT_128414

http://www.auburngear.com/aftermarke...6pagesize%3d20 (Click on the "Limited Slip Installation Manual")

Also, how can you simply ignore Chevrolet's Service Bulletin noted in BluRay's post?

Seems a few people have a small opinion of engineers, enigneering, R&D, and testing.

I'll give you the last word.

 

Additive cost me almost $11 for a small bottle at my local Chevy dealer yesterday.

That's exactly what I bought to use.

 

Yeah but Tom I know from my experience that anything used for the track is racing, nothing in racing is expected to last past the current race.

 

I haven't used my scanner in a long while, it's 10 yrs old & came with my 1st PC. Anyway, it appears that the scanner is dead and/ or the software is not working with my XP op sys....I do apologize for my lack of PC skill, as I'm sure that is at the root of me not being able to get a scan of that owner's manual up on the forum.

:o
Tom

 

Quite true. Most racing cars are hopefully designed to last as long as need be to win an event, then they get "serviced" afterwards. I'd like to have the C6R team budget.

The only sane reason that I can give for the information in my "other owner's manual" is that back then chevy figured that some percentage of owners will do HPDE's....they even give a Driver's school contact info if the owner was interested in "improving" their driving skills. In a way I feel the info presented in that manual is logical. Chevy's worst nightmare would have been for that car to have mechanical failure issues even at HPDE's.....I know that is a reach for a street car, but consider my Z's sticker was almost 60k when delivered 6/17/90....after all the smoke cleared the bill was close to 65k out the door to my car's original owner. The buyers that can afford to play at that price level do not tolerate many things going wrong with their pampered toys.....at least for the duration of the factory warranty.

JMHO

Tom

 

LOL "serviced"

 

Yes I'm sure, 96's Vipers are clutch type limited slip, newer ones are not. As far as trusting engineers the best answer I've heard is that the Titanic was designed by professionals, the arc was built in Noah's back yard, only one survived the maiden voyage.
By all means use whatever you are comfortable with, I feel good about what is in mine.

 

FYI
I have contacted Dana Spicer on this topic and asked them if there is any difference between the Viper D44 and Corvette D44. I asked them if there is any reason to not use synthetics in D36 & 44 cases. I will post the results when and if they reply.

I must say I appreciate the spirited but respectful debate you guys are having on this subject it has been very enlightening to me and I am sure other Corvette owners.

 

I wrote them a few times over the years and never got a response. The Redline lube has been working in mine for track use for several years.

 

Hey Tom, what manual is this? Is this the ZR-1 manual from the pizza box?

 

Look forward to hearing their reply if you get one. A few years ago before he retired I asked a friend who worked for Chrysler in the parts division in Auburn Hills to research the issue of Viper gears (ring and pinion) being stronger since many Vette owners seem to believe they are. His research inside Chrysler and with Dana said the gears are identical.

 

Hi Bob! Yes in the pizza box along with all the other stuff there is another owner's manual packaged in a small box w/no cover on the box. Anyway, it is a grey covered, spiral bound book about the same page size as the manual in the glove box. However, this manual is specifically for the ZR-1, our logo on the cover like our decal @ the registry.

Topics are a fairly detailed look into the motor, trans, FX3 sys., abs sys., etc. There is a section devoted to doing HPDE's with your Z along with "tips" to better protect the car under those conditions. I haven't read it since I got mine back in 12/04...I may have to do that again as the snow is flying here in earnest.


Tom

I gotta say that I've put 26,600 miles on mine since 4/05, and I have used the GM replacement lube for D44's after the local parts dept sold me 2 yr's worth of the old P/N....yea, I took it all! Even with the newer GM stuff though I notice no negative effects. But my change schedule is every yr which is about 5 to 6 k miles of use. I always add 2 bottles of GM additive. This yr is the first time I'm trying Amsoil Severe Gear 75w-90 + 2 of their additives...we shall see how this works out.

 

OK, Its Newby time....I sucked a bunch of green dino fluid from the rear of my '96 ...today and got as much of that 12 year old fluid out as would come out. I am replacing it with Amsoil 75w-90 Severe Gear...and 2- 4 oz. GM Additives. I premixed the additive with the Amsoil and pumped the brew back in....Took just about 1.6 quarts of the combo to fill the pumpkin. Based upon what others are saying...we may have left a few ounces of the the original fill in the car due to sub standard suck job... We'll see how it works out. To say the least, the new stuff...well looks new!!

 

It should be fine

 

FYI I went with Castrol 80W90 and 2 GM additives. Seems fine so far.

 

Am I missing something? Why twice the positrac additive. The factory calls for 4oz of GM fluid right. I mistakenly used 7oz (K - W Engine TransX Posi-Trac Limited Slip Gear Oil Additive 7 fl. oz.) and drained the fluid, just to make sure 4oz was put (Stalube, 4oz)


http://www.crcindustries.com/auto/co..._ss.aspx?ID=96

Also Castrol 80W90 here.-) But, I hear that the best dino is Pennzoil 80W90.

C4ZF6nut

 

hmmm don't know? didn't catch that.

 

Opps..TOO MUCH OF A GOOD THING...I will be doing a remedial R&R on differential lube...I agree, and thanks c4zf6nut for raising the question, I was in error to put 2- 4 oz GM additives in the differential...it does call for just 1...out with that mix and in with the new. Still using Amsoil Synthetic 75W-90

 

2 LS =8oz

 

7oz= ~2 -4oz bottles