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Discussion Starter #1
I doubt if anyone has done this, but what if we added 3 or 4 ounces of engine oil STP to our diff fluid when we change it. I realize the warranty would be voided, but do you think this would "quiet" the whine? I only have 3 thousand miles on my new diff.....no burn outs or clutch dumps. Starting whining a little a 1000 miles ago @ 40 MPH while decelerating. Took a rode trip yesterday and with the cruise control locked at 70 MPH, the whine was very noticeable.

Thoughts? (Positive or Negative)......thanks
 

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2005 CTS-V
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8,363 Posts
I doubt if anyone has done this, but what if we added 3 or 4 ounces of engine oil STP to our diff fluid when we change it. I realize the warranty would be voided, but do you think this would "quiet" the whine? I only have 3 thousand miles on my new diff.....no burn outs or clutch dumps. Starting whining a little a 1000 miles ago @ 40 MPH while decelerating. Took a rode trip yesterday and with the cruise control locked at 70 MPH, the whine was very noticeable.

Thoughts? (Positive or Negetive)......thanks
STP just increases the viscosity. You can acheive the same result (with respect to viscosity) by simply going to a fluid with higher viscosity than the 75w-90 (e.g. 90w-140). That has been tried and does not make the whine significantly quieter once it is warmed up.
 

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:yeah:


After I got my new one a couple of months ago, I could have sworn that it was whining soon afterward, too. Could it be that we're just hyper sensitized to it now?
Could be. I will be getting a new one in September and I will wait to see what it sounds like. I do plan to change the fluid early, at 500 miles or so, and again every 3,000 miles until the used fluid looks like it is coming out relatively clean.
 

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Discussion Starter #5
Thanks Guys.......

It was hovering around a 100F yesterday. Road trip fm Phoenix to Prescott, then to Jerome....(What a cool little town) ! ! ! I agree.....I AM listening for the "whine"....... The first 30 minutes was OK......then as the diff got hotter......(thinner fluid, of course)....it got louder. After I parked the car for a few hours and things "cooled down".......it was slightly quieter again. That's why I asked about the STP stuff. I might go ahead and try it just "for fun"......can't hurt, I guess.
 

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Corvette people have taken insulation and padded the floorboard over the rear end. If you were inclined, you could remove rear seat, install insulation there. Same in trunk. When done, re-install regular covering in trunk. Camaro and Firebird people have done the same, as those rear ends are notorious for noise.
 

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Corvette people have taken insulation and padded the floorboard over the rear end. If you were inclined, you could remove rear seat, install insulation there. Same in trunk. When done, re-install regular covering in trunk. Camaro and Firebird people have done the same, as those rear ends are notorious for noise.

I used Dynamat Extreme under my rear seat and in my trunk. Still hear the whine.
 
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