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I was in the dealer recently for sevice and had the opportunity to ask the tech about the limited slip additive. He indicated that with good synthetic gear lube it was not necessary. My question is what does it do and what are the symptoms if you are needing it?
 

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The symtoms I believe are chatter and binding. My mom had an Impalla SS that kinda popped and grabbed until we changed the gear lube with a good syn. lube. :cool:
 

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He's Full of BS. The Additive IS REQUIRED. For use with BOTH Non-Synthetic AND Synthetic Gear lubes.

The ONLY exception is if the Additive is already included in the Synthetic or the manufacturere specifies that the additive is not necessary. Not all Synthetics are capable without the additive.

You can ruin a Diff by not using it.

It reduces friction, heat, and allows the unit to run smoother. Otherwise it will whine, chatter. It would almost act like running your 4 wheel drive vehicle in 4Lock on dry pavement. Not what you want to do.

Running JUST a Synthetic in the Diff will minimize the symptoms but will not protect the Diff and it will fail.

I recommend either the

GM # 1052358 Limited Slip Axle Lubricant Additive - 4 oz.

OR

AMSOIL # ADABA Slip Lock Differential Additive - 4 oz.

NOTE: This is also a case where more is not better. Do not use more than the 4 oz. per fill unless the manufacturer specifies otherwise.

Here is additional info:

https://www.amsoil.com/storefront/ada.aspx
 

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DJ -

From the link you posted:
NOTE: AMSOIL Synthetic Gear Lubes do not require the use of this additive. However, not all differentials respond the same and if chatter is noticed, the addition of AMSOIL Slip-Lock will eliminate it. For chattering differentials not running AMSOIL Gear Lube, this product is an excellent solution to the problem.
For the record, I flushed my diff a few weeks ago, and did not add it. But then, I've been looking for chatter, and there has been none. If I had noticed any chatter, I would have dropped some of that in. Then again I used the Amsoil Severe Duty gear lube.
 

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If you change your diff lube and you're still under warranty, I would use the recommended GM lubricant. The reason is it has a grape smell. If you change your oil with a non GM lube and you have a diff failure under warranty then GM can refuse to do the work.

Just a thought.
 

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The important thing to remember that more is not better when it comes to Limited Slip Axle Lubricant Additive. You should add no more than is necessary to stop or eliminate the chatter or noise. Using more than necessary will reduce the effectiveness of the Differential. :z:
 

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They can not decline a warranty repair if the fluids you use are equal to or above what they specify.

In addition you may not notice any chatter or problems under normal street driving....but may, and may damage the diff under track conditions.
 

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IT L GO said:
The important thing to remember that more is not better when it comes to Limited Slip Axle Lubricant Additive. You should add no more than is necessary to stop or eliminate the chatter or noise. Using more than necessary will reduce the effectiveness of the Differential. :z:
I agree and often see people arbitrarily add more thinking more is better. The Amsoil site states none is required because it is in there already, at about 4%. Most cars won't chatter with this ratio, mine didn't, but there is always an exception. If it does chatter with the Amsoil, than a whole bottle does not need to be added but rather only enough to eliminate the chatter.
 

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Does anyone know why my 03 ZR2 Blazer with a Locking Differential states that the diff lube is the same for the locking as it is for the non-locking diff but goes on to say specifically not to add the friction lube?! :screwy:

My Dad's 03 ZO6 was just in the shop for a small pax side diff leak and the receipt shows that they added the friction additive as well to the already better synthetic GM diff fluid that the Vette uses.
 

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DJWorm said:
He's Full of BS. The Additive IS REQUIRED. For use with BOTH Non-Synthetic AND Synthetic Gear lubes.

The ONLY exception is if the Additive is already included in the Synthetic or the manufacturere specifies that the additive is not necessary. Not all Synthetics are capable without the additive.

You can ruin a Diff by not using it.

It reduces friction, heat, and allows the unit to run smoother. Otherwise it will whine, chatter. It would almost act like running your 4 wheel drive vehicle in 4Lock on dry pavement. Not what you want to do.

Running JUST a Synthetic in the Diff will minimize the symptoms but will not protect the Diff and it will fail.

I recommend either the

GM # 1052358 Limited Slip Axle Lubricant Additive - 4 oz.

OR

AMSOIL # ADABA Slip Lock Differential Additive - 4 oz.

NOTE: This is also a case where more is not better. Do not use more than the 4 oz. per fill unless the manufacturer specifies otherwise.

Here is additional info:

https://www.amsoil.com/storefront/ada.aspx
Although Amsoil Severe Gear does require the Limited Slip additive, nor needs it apparantely, can you or should you add to the differential with the Amsoil Severe Gear procuct? There does not seem to be a clear consensus on the forum on how to proceed.
 

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My recommendation is if you track the car it should be added.

You may be able to get by without the additive and AMSOIL synthetic on the street under normal driving conditions.

I have noticed that I can stress the Diff more under low speed AutoX conditions than during high speed track conditions. Probably because the turns are not as sharp and the wheel speed differences are not as great on a high speed sweeper but are while accelerating hard while coming out of a sharp low speed turn.

I also believe that once the chatter has started, damage may already have occured to the Diff clutch pack.

Another consideration is heat and wether or not the Diff has a cooler. Heat will degrade the fluid and additive package sooner. Although a synthetic will hold up to heat better and has a wider heat range, synthetics will still degrade with excessive heat. Using the recommended friction modifier may offer some protection during severe operation.
 
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