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2004 BLK Cadillac CTS-V
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Discussion Starter #1
I am thinking of trying some AMSOIL synthetic gear lube in the diff to stop my wine since it seems to be holding up well and is just annoying at times when not listening to the radio to have to listen to the wine. My V has 46k miles and hasn't blown a diff yet. I got it used, but think it has had all the TSB fixes for diff protection other than a new diff or anything big. Just want the wine to go away. What gear lubes are known to work well? And what weight and viscosity and such would be best as AMS OIL offer a few different options with their synthetics?
 

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A "whine" at 46K is warranty-actionable. At 42 K, I had a similar whine, which was pronounced at a steady 30 mph. Dealer replaced the differential under warranty, and the shop write-up reported the problem as bad bearings. Whatever, it is in your interest to document your warranty claim by taking it to your dealer while within your warranty period. Then, if the condition becomes untolerable after warranty expiration you have a history of having complained about the problem during warranty.

I had a differential apart a few weeks ago at www.tpis.com. We concluded that bearing size appears robust, well supported and adequate with good opportunity for lubricaton. Why bearings fail was not apparent to our examination. We speculated that perhaps the pounding from a wheel-hopping launch might damage bearings. TPIS commented that gear ratios deeper than about 3.4:1 tend to be comparatively noisy.
 

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Went with Mobil 1 75W140 a couple of weeks ago (mainly because I couldn't find a local supplier of Redline or Royal Purple). I went with the heavier viscosity to deal with the heat of the FL summer and to see if it would quiet things down. Did not add friction modifier as Mobil claims it is not needed. So far no grabbing or shudder. I initially thought it might be just a bit quiter, but that was probably optimistic. I'll be trying the brute force sound deadner approach to whine reduction as soon as I have the time to install some Dynomat/Ram-mat under the rear seat.
 

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BANK OWNED!! CTSV & EXT
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I'm using AMSOIL severe gear 75-90 and its working good after probably 6-7000 miles. They say that you don't have to add a modifier. I put in slip lock (their brand of additive), just for the hell of it.
 

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06 CTS-V (sold)
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I put in AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 at the 10,686 mile mark. Now have about 11,700 on it. I intend to resample my diff fluid at about the 15.5k mark to see if the wear my diff exhibited on the factory fluid is improved, same or worse. Going to take me a while to get there though as I don't get many miles in each month as my commute is only about 5 miles.
:cheers:
 
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