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CTS 2008 3.6DI Sport Luxury
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Discussion Starter #1
I know some of you used amsoil severe gear lube with slip-lock additive for your limited slip differential.
I have just received following message from AMSOIL:
"You are correct, the lookup guide is confusing and we’re looking at options for clarifying the friction modifier statements in the lookup guide. Briefly, the Severe Gear oils are friction modified and will work well in most cases without additional friction modifiers. However, due to varying degrees of wear, current clutch material condition, spring strength etc… we cannot say definitively without a doubt that additional friction modifier won’t be needed in some cases. In the limited cases where chatter does occur, ADA would need to be added.*"
I have dilema, because I have already purchased amsoil lubricant but didn't change oil yet.
Could you share your experience in using this lubricant with or without slip-lock additive in GM vehicles w/LSD, especially CTS RWD 3.6 DI FE3.
I am affraid my LSD will be no more limited slip if I use additive or will have chatter in other case. Can lack of FM cause differential damage?
 

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2012 CTS, thunder grey chromaflair
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120 Posts
I know some of you used amsoil severe gear lube with slip-lock additive for your limited slip differential.
I have just received following message from AMSOIL:
"You are correct, the lookup guide is confusing and we’re looking at options for clarifying the friction modifier statements in the lookup guide. Briefly, the Severe Gear oils are friction modified and will work well in most cases without additional friction modifiers. However, due to varying degrees of wear, current clutch material condition, spring strength etc… we cannot say definitively without a doubt that additional friction modifier won’t be needed in some cases. In the limited cases where chatter does occur, ADA would need to be added.*"
I have dilema, because I have already purchased amsoil lubricant but didn't change oil yet.
Could you share your experience in using this lubricant with or without slip-lock additive in GM vehicles w/LSD, especially CTS RWD 3.6 DI FE3.
I am affraid my LSD will be no more limited slip if I use additive or will have chatter in other case. Can lack of FM cause differential damage?
Do all CTS RWD have LSD, or only certain models?
 

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2008 CTS4
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457 Posts
To my knowlege, not all CTSs have LSD rear diffs. While I'm a huge Amsoil proponent, I used the dealer oil and friction modifier when changed my fluids. I do not believe too little or too much friction modifier will do damage in the short term, but I've never let a situation like that last long.
 

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CTS 2008 3.6DI Sport Luxury
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1,027 Posts
Discussion Starter #4
It depends on suspension package. LSD was delivered with FE2 and FE3 (for 2008-2009 for sure)
 

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CTS 2008 3.6DI Sport Luxury
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1,027 Posts
Discussion Starter #8
i have the fe3 model but the dealer put only oil without modifier,is it necessary?
tnx
Do you know what oil they used? If it doesn't contain friction modifier you should use it to eliminate chatter.
 

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I have had the AMSOIL Severe gear in my 2009 CTS4 (w/LSD) for 5 yrs (and over 40,000 miles) and it performs flawlessly, both front and rear. I did not use any additive when I had it installed and I NEVER hear any noise whatsoever. I also have it my 2012 Sierra Denali as well.

Go ahead and use it, its the best choice out there. You are worrying over nothing. If you get chatter, then add the FM.

Read about the purpose of FM's.
Chatter is essentially the build-up and release of energy between the differential clutch packs in a limited slip differential during operation. This phenomenon often occurs when torque is transferred between the clutches or when rotational speeds change. During the stick-slip phase, energy is built up to a point where contact between the clutch plates change between static friction (stick) and dynamic friction (slip), resulting in noticeable vibrations. It is this vibration that causes an audible chatter or ratcheting to be heard within the differential. While certainly an annoying characteristic, there is typically no mechanical damage occurring to the differential. It is most often noticed in parking lots or slow driving while turning where the outside wheel turns faster than the inside wheel.

In an effort to control this chatter, friction modifiers are often used. These additives result in a smoother transition between the two states of friction: static and dynamic. Static friction occurs when the clutches physically lock together, while dynamic friction occurs as the clutches are slipping, ergo Limited Slip Differential.
 

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2014 CTS Coupe 3.6 RWD Perfomance Pkg, TriCoat White Diamond
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1,598 Posts
I have had the AMSOIL Severe gear in my 2009 CTS4 (w/LSD) for 5 yrs (and over 40,000 miles) and it performs flawlessly, both front and rear. I did not use any additive when I had it installed and I NEVER hear any noise whatsoever. I also have it my 2012 Sierra Denali as well.

Go ahead and use it, its the best choice out there. You are worrying over nothing. If you get chatter, then add the FM.

Read about the purpose of FM's.
Wow. We need that quote (in post #10) somewhere so that everyone that complains about feeling "vibrations" can have access to this explanation.
 

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CTS 2008 3.6DI Sport Luxury
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1,027 Posts
Discussion Starter #13 (Edited)
So, I've changed differential oil for amsoil 75w-90 severe gear without adding any separate additives. It performs excellent so far, even better than before. Thanks again for your support.
 
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