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cts-v
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Discussion Starter #1
I've read a ton of threads about different brands and mixes for the rear diff fluid, but my question is which method is recommended by the manufacturer?

Using GM #88862624 with the additive already mixed in or using GM #89021677 and adding in GM #88900330.

I am thoroughly confused and wondering which method is the right method... thanks in advance.
 

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Dealer drained and used the diff fluid that already have the LSA mixed in. No chatter or anything to report since. Make sure to use the one with the LSA already mixed in.
 

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Gone; ‘09 V, ‘13 V coupe. Curr; ‘14 PG Vsport prem w/Kona interior
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Had my diff fluid replaced last year. Dealer used Valvoline SAE 75W-90 full synthetic gear oil with limited slip additive included. Runs like a champ!

Part No. 819195
 

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2009 cts-v
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FWIW, for the small cost involved , I'm going to add the 4 oz. additive bottle to the GM diff fluid that already has the LSA additive in it when I change it next week ( probably not needed but a little extra insurance can't hurt ).
Got in the habit of putting in 2 bottles of the GM limited slip additive( when it called for one) when I had my 87 Turbo Buick and never had a single issue with the diff in the 26 years that I owned it and raced it .
 

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'04V, '05V, '06SRT8, '10V, '13ZL1, '12 V, '16 Z06 SC757
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GM fluid with FM is available through Amazon for $15. I ordered 2 bottles on Sunday. This will be my second fluid change with only 16k miles. Hoping to quiet down the rear. We'll see.
 

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cts-v
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Discussion Starter #6
Thanks for the replies. The confusion came in when I read people using the fluid with additive included but the owner's manual specifies two separate part numbers for the gear fluid and the additive... Why not just have one part number that already includes the modifier...
 

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2011 CTS-V Wagon-Raven Black, manual, satin graphite wheels
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There's really no reason to put extra additive in. If there is chatter from the limited slip it is likely from contamination and a drain and refill will solve the problem.
 

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2011 CTS-V Wagon-Raven Black, manual, satin graphite wheels
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The diff oil with the LS additive in it is nothing new.

But I guess it is still new enough to have not been in the CTS-V service info. It actually doesn't look like the oil is specified in the owners manual but I'm looking at stuff online and not in a physical owner's manual


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I was trying to see what the first car that started getting the LS fluid according to service manuals was. It appears the Corvette got updated because it says to use the LS fluid back to 2010 even though the Camaro in 2010 still had them broken apart. In any case, on the topic of adding friction modifier to the LS fluid, don't do that. Not only not necessary, but could cause issues, just because you've been doing it and haven't had problems doesn't mean it can't cause problems so spare me that argument.



Funny that the C5 service manuals also appear to have been updated, but not anything else. So Corvette actually says to use it all the way back to 1997.
 

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Discussion Starter #11
I actually did look through each year's manuals and found that no part # for the fluids (both the fluid and additive) are mentioned in 2009 thru 2011. It's not until 2012 the fluid and additive are listed separately. No manual actually states the fluid with the additive already mixed in; could the service department's intranet pull up the pre mixed solution instead when we bring our cars in for service?
 

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Gone; ‘09 V, ‘13 V coupe. Curr; ‘14 PG Vsport prem w/Kona interior
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That's what they did with my 2013 coupe. Part# 819195.
 

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I saw the service tech do the service on my rear diff and he said he uses the fluid that already has the LSA in it for every GM diff that requires the LSA and it's a retroactive fluid for all years.
 

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Been using Mobil gear oil with the additive in it and adding the GM LSA fluid too in different vehicles for years now with no issues in any of them including the V
.
 

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2011 CTS-V Wagon-Raven Black, manual, satin graphite wheels
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I don't understand why people are doing that. There is NO BENEFIT to adding anymore friction modifier than is required to not have chatter. I've even known people that would use fluid without the additive in it and only add the amount of additive required to prevent chatter (not just pouring in the whole bottle of additive). Extra friction modifier is reducing the effectiveness of the limited slip and as the snip of the service manual I posted above shows, is explicitly stated as something you shouldn't do by GM.
 

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GM TSB 10-04-20-001E says to use GM 88862624 (Dexron LS). It does NOT mention adding any additional friction modifier.

The TSB was to address a " Rear Axle Clunk and/or Chatter Type Noise on Turns (Drain/Refill Rear Differential Fluid)".
 
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