Differential Fluid Refill
Thread Starter
5th Gear
Joined: Sep 2007
Posts: 5
Likes: 0
From: Lawrenceburg IN
Differential Fluid Refill
Okay. I'm just now starting to get a little differential noise and minor grabbing/growling when making tight turns both forward and backward. What gear lube do I want to use? Additive? Hate the thought of having the melvins at the local Chevy dealership working on it. Took it in for rear link washer recall and got it back with a shock hanging unattached. I'll do it myself. Any horror stories?
Safety Car
Joined: Apr 2004
Posts: 3,996
Likes: 77
From: Louisville KY
I just did mine. I bought the original GM fluid and the little bottle of additive. The stuff lists for 29 a bottle and I get it for 22 a bottle. It takes 1.63 quarts according to the service manual.
Very easy to do. Jack up car, put on 4 jack stands. Take out drain plug, oops put catch pan under diff., take out fill plug, go drink coffee - 2 cups, come back, replace drain plug, put in fluid till it reaches the bottle of the fill hole, replace plug, ( put additive in after the first quart, not at the end).
Very easy to do. No problems. My mn6 with 35k had started the noises on hard sharp turns, after the fluid change it is totally quiet.
Very easy to do. Jack up car, put on 4 jack stands. Take out drain plug, oops put catch pan under diff., take out fill plug, go drink coffee - 2 cups, come back, replace drain plug, put in fluid till it reaches the bottle of the fill hole, replace plug, ( put additive in after the first quart, not at the end).
Very easy to do. No problems. My mn6 with 35k had started the noises on hard sharp turns, after the fluid change it is totally quiet.
Race Director
Joined: Dec 2000
Posts: 19,304
Likes: 85
From: San Diego CA
I did my diff and manual tranny fluid change not too long ago. I used Amsoil SVG 75W-90 synthetic gear lube for the diff and Amsoil Universal ATF fluid for the tranny. Both are excellent fluids and the ATF stuff does make shifting easier.
Instructor
Joined: Jul 2005
Posts: 231
Likes: 0
From: Hinckley, Ohio
Several people have drained their diff and then found out that their fill plug is stuck .
Therefore, before draining, I would at least loosen the fill plug.
I used Royal Purple 75W90 for limited slip diffs. No additive needed since it's already in there.
Therefore, before draining, I would at least loosen the fill plug.
I used Royal Purple 75W90 for limited slip diffs. No additive needed since it's already in there.
Race Director
Joined: Dec 2004
Posts: 13,760
Likes: 75
From: Haymarket VA
Pro
Joined: Jun 2003
Posts: 624
Likes: 7
From: St. George, UT
DAVE....
Do you have to use a additive with the amsoil?
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Premium Supporting Vendor
Joined: Aug 2001
Posts: 5,364
Likes: 38
From: King George VA
The AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 comes with additive in it and use of additional friction modifier is not normally required for the C5. I've been using this fluid in my 02 Z06 on the track for years without additive and recently put it in my 06 CTS-V daily driver, again without additive. Neither diff has ever chattered.
That said, the C6 diff appears to perform differently and for my C6 customers I do recommend adding one bottle of AMSOIL Slip-Lock Differential Additive to stop the chatter they all seem to be getting with the stock fluid.
That said, the C6 diff appears to perform differently and for my C6 customers I do recommend adding one bottle of AMSOIL Slip-Lock Differential Additive to stop the chatter they all seem to be getting with the stock fluid.
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AMSOIL Preferred Customer Program (Members buy at Wholesale - a savings of about 25%)
Le Mans Master
Joined: May 2006
Posts: 7,875
Likes: 254
From: Hillsboro OR
I used synth 75W-90 and the GM LSD additive. After you change the fluid do very slow figure-eights. I would do 3-4 forward and 3-4 backward. It will help work the fluid and additive into the synchro gears.
