How often to change Rear diff fluid?
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 792
Likes: 19
From: ME
How often to change Rear diff fluid?
What is the recomended GM interval for draining and filling the rear diff? I can't seem to find it... Do some of you change it more often than recomended?
Team Owner
Joined: Dec 1999
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Racer
Joined: Aug 2005
Posts: 251
Likes: 32
From: S/W Illinois
GM says never on 6 speed and rear end. I just did my '99 at 35,000 with Dexron III in the trans and synthetic 75/90 in the rear end with the GM posi fluid. I spent about $30 for all the stuff for both units. For what these cars cost, I can't see not changing it. I did spend a couple of hours on the job.
Premium Supporting Vendor
Joined: Aug 2001
Posts: 5,364
Likes: 38
From: King George VA
Given how hot our diffs get with low airflow, high friction, low fluid capacity, and the exhaust running right by them, I have always been a little skeptical of the GM change recommendation, which is never.
Most of the experienced SCCA T1 teams replace their fluid very frequently, so I defaulted to following their lead. I change my tranny and diff fluid about every four track days... and so far so good for me as I'm still on my original stock tranny and diff, four years of abuse later...
For a daily driver, I'd feel more comfortable with 30k miles.
I use AMSOIL ATF and AMSOIL Severe Gear Extreme Pressure Synthetic 75w90.
Most of the experienced SCCA T1 teams replace their fluid very frequently, so I defaulted to following their lead. I change my tranny and diff fluid about every four track days... and so far so good for me as I'm still on my original stock tranny and diff, four years of abuse later...
For a daily driver, I'd feel more comfortable with 30k miles.
I use AMSOIL ATF and AMSOIL Severe Gear Extreme Pressure Synthetic 75w90.
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C66 Racing #66 NASA ST2, SCCA T2
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AMSOIL Preferred Customer Program (Members buy at Wholesale - a savings of about 25%)
