Differential Fluid
Thread Starter
Instructor
Joined: Aug 2002
Posts: 180
Likes: 1
Differential Fluid
I have a noisy differential, like many other C5 owners (noisy when pulling out or driving slow with a load). I decided to change the trans and diff fluids to RedLine about 2 years ago thinking that it might help with the noise, but it didn't. Now my diff clutches have started to stick when pulling out to turn, so I get some wheel hopping. I read a little about the limited slip additive/friction modifier that you might need to add with certain fluids, but the RedLine I bought was not suposed to need this. I'm thinking about changing diff fluids again, and I'm not sure which way to go. Back to GM, Amsoil, etc. Any advice? Should I add the friction modifier this time? Also, I want to do this myself. Is it hard to find the drain and refill plugs? Thanks for the DIY tips.
Drifting
Joined: Jul 2001
Posts: 1,976
Likes: 4
From: San Diego CA.
Re: Differential Fluid (bernardomd)
I also have a diff which is howling and last summer I had the diff oil drained and replaced with new GM non synthetic fluid. The mechanic also included 2 bottles of the GM posi additive. The howling under light load has been reduced considerably but is still noticeable. My mechanic is an ex-GM specialist who was trained to work on the LT5 engines and he didn't like the idea of using synthetic fluids in the diff. He only charged me 85.00 including tax for the oil change and additive. It's not worth doing it yourself for that kind of money. Good luck.
Le Mans Master
Joined: Jul 2002
Posts: 7,370
Likes: 8
From: Slave to the evil empire
Cruise-In V Veteran
St. Jude Donor '04
Re: Differential Fluid (Finelee)
He only charged me 85.00 including tax for the oil change and additive. It's not worth doing it yourself for that kind of money. Good luck.
I've also read that some of the synthetics that claim to already have the additive included may actually need a little additional put in, in other words if your gears are noisy then try adding 1 oz. of additive and so on until the noise gets better.
[Modified by runamuk, 3:46 PM 1/10/2004]
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Re: Differential Fluid (runamuk)
It depends on which Redline you used. If you used the straight 75W-90, it has the modified in there (4% if I remember correctly). If you used the 75W-90NL, then you need to add it. The Redline fluid is NOT compatible with the GM modifier and you must use the Redline product.
If you change it out, I am now using Amsoil and am very happy with the results. If you use the Series 2000 75W-90, again the friction modifier is already in the bottle in the proper amount, no additional is required. If you change, make sure you do about 10 slow figure 8's to work the new fluid into the clutch pack as soon as you change it.
If you change it out, I am now using Amsoil and am very happy with the results. If you use the Series 2000 75W-90, again the friction modifier is already in the bottle in the proper amount, no additional is required. If you change, make sure you do about 10 slow figure 8's to work the new fluid into the clutch pack as soon as you change it.
Le Mans Master
Joined: Oct 1999
Posts: 8,205
Likes: 40
From: Tucson AZ
Re: Differential Fluid (bernardomd)
I would go with Amsoil. Start with just the Amsoil gear lube. If you probems don't go away, add some of their (or GM's) limited slip additive. :yesnod: :)
Instructor
Joined: Dec 2003
Posts: 157
Likes: 0
From: Sarasota FL
Re: Differential Fluid (bernardomd)
I went with mobil one synthetic 75w90 with one bottle of gm additive. Easier to change than the engine oil. No noise from the rear end before or after the change. :thumbs:
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 179
From: S.W. Ohio. . . . . . NRA Life Member
Re: Differential Fluid (00pewterpower)
if you're getting clutch-pack-catching on turns; after you change the diff oil; do a bunch of steering wheel stop-2-stop figure eights.
Be careful not to hit any lamp poles in whatever parking lot you chose :)
Be careful not to hit any lamp poles in whatever parking lot you chose :)
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Le Mans Master
Joined: Mar 2002
Posts: 5,266
Likes: 1
From: Kennesaw Ga
Re: Differential Fluid (bernardomd)
Make the move & be done!
AMSOIL Series 2000 Synthetic Gear Lube is Recommended for Applications Requiring the Following Specifications:
API MT-1, GL-2 THROUGH GL-5
MIL-PRF-2105E
MACK GO-J, GO-J PLUS
CHRYSLER MS-9070
GM 12346190
FORD M2C-201-A
ROCKWELL 0-76-E
EATON PS-037A, PS-109
AMSOIL Series 2000 Synthetic Gear Lube provides limited slip performance. Although generally not necessary, original equipment manufacturers' limited slip additives may be used in conjunction with AMSOIL Series 2000 Synthetic Gear Lube.
NOTE: Most vehicle manufacturers recommend driving a vehicle in tight figure "8" patterns eight to ten times after changing limited slip lubricants.
AMSOIL Series 2000 Synthetic Gear Lube is Recommended for Applications Requiring the Following Specifications:
API MT-1, GL-2 THROUGH GL-5
MIL-PRF-2105E
MACK GO-J, GO-J PLUS
CHRYSLER MS-9070
GM 12346190
FORD M2C-201-A
ROCKWELL 0-76-E
EATON PS-037A, PS-109
AMSOIL Series 2000 Synthetic Gear Lube provides limited slip performance. Although generally not necessary, original equipment manufacturers' limited slip additives may be used in conjunction with AMSOIL Series 2000 Synthetic Gear Lube.
NOTE: Most vehicle manufacturers recommend driving a vehicle in tight figure "8" patterns eight to ten times after changing limited slip lubricants.
Safety Car
Joined: Sep 2001
Posts: 4,596
Likes: 2
From: Atlanta GA
