How many containers of GM Synthetic Diff Fluid will i need to buy to drain & fill? I know i need 1 container of additive, but not sure how many of the diff fluid. Thanks!

 

also, should i use the synthetic fluid, as stated in owners manual, or switch to regular, to avoid possible grinding problems?

 

I just put in Redline trans and diff. fluid...the diff. took 2 quarts (gave the mechanic two quarts and didnt get any back, so I assume) what additive are you talking about? did I mess up...I just had the fluid put in alone? :eek:

 

1.7 quarts plus the additive, according to the manual.

 

Chrisquik,

-You are okay, Redline comes with (5%) additive already in it !

 

Stay with synthetic. Don't know who told you to use regular to prevent grinding !? Synthetic is better lubrication.

 

I had mine serviced at a dealership and we put in the synthetic. That's when the grinding noises started (yes, we also added the limited-slip additive). Had to change it back out to mineral based oil, did that twice (flushed the rear end) and the noise SLOWLY went away.

 

One version does and one doesn't. Make sure you get the stuff with the additive already in it. :cool:

 

The synthetic to dino oil swap had nothing to do with the noise factor. It's the limited slip additive that eliminates the noise and it's for just this reason that they make the stuff. Stick with synthetic gear oil as recommended and your transaxle will thank you. :cool:


[Modified by XTrooper, 8:50 AM 4/14/2002]

 

Thanks, but in this case the fluid was the problem, and I did add the friction modifier to the synthetic. I researched this quite a bit when I had the problem last summer. I had a response by c4c5 tech who advised the fluid swap fix which I followed. In my case anyways, it came down to the fact that the friction modifier would not stay mixed in the synthetic fluid and separated out after about 1000 kms, which caused the grinding sounds.

Once again, and in my case, the synthetic to dino oil swap had everything to do with the noise factor and fixed the problem.


[Modified by mjager, 9:04 AM 4/14/2002]

 

Some have constant returning posi clutch plate noise...GM #12345977 GL5 with the additive corrects this problem,as per GM...and it works ;)

 

Well, I'm glad you got things sorted out! :cool:

 

Go with Amsoil Series 2000 75w90 Gear lube :smash: :smash:
It has the friction modifier in it :yesnod: :yesnod:
Read the label on the bottle,it's in it. :cool:
I did mine about 3 weeks ago :D NO Noise :smash:
You will need 2 quarts. :chevy
:seeya

 

Here are pics and tips:
http://www.picturetrail.com/gmblack3/647207

Limited Slip Axle Lube Additive
The GM part # is 1052358. You should add this before putting the new fluid in the diff.
The local stealer here charges $9 for it. GMpartdirect.com shows a list of $5 but you have to buy 12 of them.

Amsoil and Redline claim that there fluids already have an additive in them. Amsoil says it both ways on there website:

AMSOIL gear oils are formulated with friction modifiers for limited slip differential applications. There is no need to add limited slip or additional additives.

AMSOIL Series 2000 Synthetic Gear Lube provides limited slip performance. Although generally not necessary, original equipment manufacturers' limited slip additives may be used in conjunction with AMSOIL Series 2000 Synthetic Gear Lube.

Redline says:

LIMITED-SLIP COMPATIBILITY Red Line Gear Oils, with the exception of the 75W90NS, already contain friction modifier required for operation in limited-slip differentials. Additional additive is not required.

I have emailed Redline and asked them if it would not hurt to add the GM additive to Redline.

Here is the reply from redline

The 75W90 would be suitable for the limited slip in your Z06 it contains 5% friction modifier, typically what is needed to reduce the chatter from the limited slip when making a slow tight turn. Adding more friction modifier if it isn't needed reduces the lock up of the limited slip and reduces it's effectiveness, so I wouldn't add it unless it is needed due to chatter and then only just what is needed. The friction modifier isn't a lubricant but just an additive to make the fluid slipperier for chatter control. The 75W90 should be suitable right out of the bottle without the need for the additive. Thank you for your interest in Red Line Oil.

It states in the GM manual that no WOT for 300 miles after the diff fluid is changed.

 

Both Redline 75-90 and Amsoil Series 2000 75-90 have the friction modifier in it. (Redline 75-90NS does not). I have used both straight from the bottle and never had a problem. You cannot mix some friction modifiers with some oils and it is best to contact the manufacturer and stay with one product. I have been previously told by Redline that the GM modifier is not compatible with their oil and you must use the Redline modifier which is available separately. They are correct though, anything more then 5% detracts from the performance of the limited slip rear end.