gear oil and additive???
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Joined: Jan 2007
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From: West Palm Beach Florida
gear oil and additive???
I'm almost finished replacing my 2.59 rear with a 3.07 out of my 1990 L98
I now need to know what kind, and how much gear oil, and additive I need to use.
Any details and specifics are greatly appreciated.
Thanks!!!
Jeffrey
I now need to know what kind, and how much gear oil, and additive I need to use.
Any details and specifics are greatly appreciated.
Thanks!!!
Jeffrey
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Joined: Oct 2007
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
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St. Jude Donor '09-'10-'11
I use Amsoil severe gear oil which has the additive in it already. 
Edit: Putting Amsoil in my engine, trans, and diff I picked up 2 MPG on the highway.
Edit: Putting Amsoil in my engine, trans, and diff I picked up 2 MPG on the highway.
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From: King George VA
AMSOIL makes several gear lubes, but this is the one I use in my 02 Z06 on the track and would recommend:
AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 (Product Code SVGQT)
Note that as mentioned above, this fluid does come with friction modifier in it and most do not need extra modifier to prevent diff chatter.
AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 (Product Code SVGQT)
Note that as mentioned above, this fluid does come with friction modifier in it and most do not need extra modifier to prevent diff chatter.
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Drifting
Joined: Aug 2009
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From: Tampa Fl
I just read my manuall and it calls for 4 oz. of the limited slip modifier with a diff change. 80W-90 weight gear oil.
I used valvoline synthetic blend.
this was out of the 95 manuall,should be the same.
I think 1 bottle is 4 oz.
The modifier should be 2 - 6 % of the total fluid change
I bottle is more than enough
I used valvoline synthetic blend.
this was out of the 95 manuall,should be the same.
I think 1 bottle is 4 oz.
The modifier should be 2 - 6 % of the total fluid change
I bottle is more than enough
Last edited by tblt44; Jan 28, 2010 at 08:59 PM.
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From: King George VA
Keep in mind that many gear lubes, such as the AMSOIL Severe Gear 75w90 mentioned above, already come with friction modifier in them, so if you had more modifier without knowing this you are losing performance. Not sure of the specific details of the diffs for the C4, but for my 02 Z06, the limited slip diff is designed to pass 75 ft-lb of torque to the wheel with grip. If you add too much modifier, the diff clutch plates will not hold that much torque and you are lowering the capability of your diff to pass torque to the tire with grip. Ideally, you want just enough modifer to prevent chatter and no more. FYI, you can check how much torque your diff is passing to the tire with torque by lifting one rear tire off the ground and with the car in neutral and parking brake off putting a torque wrench on the axle nut. Mine will break at just over 75 ft-lbs of torque - thus performing as designed. If it breaks at less than you expect, you diff is more limited slip than intended. However, most will probably never notice this on the street. On the track, particularly coming out of sharp low speed corners, it will impact you a lot as too much torque will go to the inner unweighted tire and be wasted.
Last edited by C66 Racing; Jan 30, 2010 at 10:09 AM.
