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Discussion Starter · #1 ·
Quick question: I'm getting ready to start my complete fluid change today, and I'm replacing the rear diff fluid with Amsoil Severe Gear. I know I need to add limited slip additive, but I don't have the actual GM stuff. I have some Mopar-branded additive that I used in a Dana axle recently, and was wondering if it's basically the same stuff required by our cars. If not, I'll just wait until tomorrow and get some at the dealer, but if it's all the same, I'd rather use it up.

Thanks.
 

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'05 CTS-V, Powered by Chevrolet
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Quick question: I'm getting ready to start my complete fluid change today, and I'm replacing the rear diff fluid with Amsoil Severe Gear. I know I need to add limited slip additive, but I don't have the actual GM stuff. I have some Mopar-branded additive that I used in a Dana axle recently, and was wondering if it's basically the same stuff required by our cars. If not, I'll just wait until tomorrow and get some at the dealer, but if it's all the same, I'd rather use it up.

Thanks.
Since you are using Amsoil, they suggest initially running it without the additional slip additive. But, if afterwards you then witness clutch chatter by using straight Amsoil then add their limited-slip additive. Their oil is already formulated with a slip package. I would only use the additive made by Amsoil in an Amsoil fill, not GM, not Mopar, not Ford, but only if needed. In my case, I did not need the additive. I'm running their 75W-140 Severe Gear.
 

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I'm running without additive on my '09. Amsoil has recently recommended using an additive in their Severe Gear for our cars, but not the older Vs. I will add some soon but it's OK without. For your V, it'll be fine without.
 

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I've heard similar stuff as above. I've put Amsoil Severe Gear in my car twice and added their additive both times. Guess it's like chicken soup ... can't hurt.
 

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I was trying to eliminate or at least move the MPH range the whine would occur. I tried both Severe Gear 75w90 and 75w140 and neither did anthing to make it worse or better. No change whatsoever. I have the latest diff version.
 

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Red Line, like the Amsoil, does not need additive in the V1 since it has friction modifiers built in. I did not get Amsoil in the '04 but I did have Red Line in it and it worked fine with quite a few track days. Put it in if you want but don't go crazy if you haven't...
 

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Discussion Starter · #9 ·
I didn't change the rear end fluid on Sunday, I ended up only doing the transmission and then had a little mix up with the supply and return lines for the power steering, which resulted in a HUGE mess, and once I was done cleaning that up and changing that, I only had it in me to change the fuel filter and then stop working on the car and have a beer.

So, I'm headed back today to do the rear end, and will go ahead and just put in the Severe Gear without any additive.
 

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Discussion Starter · #10 ·
Put in the Severe Gear today with no additive. I've only driven it about 20 not particularly hard miles, but it seemed to be running nice and smooth. Also managed to change the coolant, which was super easy on this car. No reason not to do it every year. It was more work changing the cabin air filter.
 

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Sorry - was out of town this week and catching one late, but concur with the input from *************** members above. The AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 (Product Code SVGQT) comes with friction modifier already in it and adding extra modifier is not normally needed to prevent diff chatter in the V1. I ran this same fluid in my 06 CTS-V until I sold it in 09 without extra additive and continue to use it in my 02 Corvette Z06 track day car without extra additive. In those rare cases where diff chatter does occur, adding a few ounces of the AMSOIL Slip-Lock Differential Additive (Product Code ADATB) will quiet the diff down. The Slip Lock Additive comes in a 4 oz tube with a long tip on it so opening the diff fill plug and squirting a few ounces in is very easy.
:cheers:
P.S. I recommend that after a diff fluid change you go out and run several tight figure 8s in a parking lot to work the new fluid into the clutch pack.
 
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