Changing diff fluid question
Burning Brakes
Joined: Oct 2004
Posts: 1,073
Likes: 569
From: Bowmanville, Ontario, Canada
My mechanic always advised me to do the figure 8's on my C3 and C5...so have to think that the concept is similar. I've only had my C7 since the fall, so will be a while before I have to do this.
Melting Slicks
Joined: Mar 2001
Posts: 2,667
Likes: 849
From: New Jersey
Figure 8s is only for mechanical limited slip diffs, to break - in the lockup clutches with the new gear oil, so they dont chatter.
No need for this on the C7.
No need for this on the C7.
Last edited by ersatz928; May 5, 2020 at 10:02 PM.
Race Director
Joined: Jan 2014
Posts: 10,709
Likes: 7,101
From: Fulshear, TX
50k miles and 2 diff fluid changes performed so far... I've never wasted the time doing the figure-8's. The differential has taken the proper quantity to fill both times and hasn't had a change in performance after either job. The initial factory-fill was pretty nasty when drained @ 22k miles though; so was the transmission (M7).
Burning Brakes
Joined: Oct 2004
Posts: 1,073
Likes: 569
From: Bowmanville, Ontario, Canada
I think my base Stingray has a mechanical LSD...isn't the e-LSD an upgrade? Is the base LSD on the C7 different from older generations?
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Racer
Joined: Sep 2012
Posts: 310
Likes: 136
Most manufactures suggest replacement on a basis of age and mileage. Most non performance cars are around four year/50k miles. However, more European manufactures are claiming there is lifetime fluid in their differentials. I am hesitant to believe that. On a performance car, or a car you care about for that matter, I suggest draining your rear diff fluid early, around 4K miles. A friend of mine build custom diffs for highly modified 4x4s and he suggests the first diff drain at 500 miles to remove all the shavings.
Safety Car
Joined: Dec 2012
Posts: 3,841
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From: St. Louis Metro East IL
Safety Car
Joined: Mar 2004
Posts: 4,048
Likes: 1,476
From: South Florida
According to the service manual you are supposed to leave the car raised off the ground, turn off traction control, and accelerate to 10mph and hold for 1 minute. Then check/top off the fluid and then you are done.
Safety Car
Joined: Jul 2018
Posts: 4,303
Likes: 2,055
From: Margate, FL
Instructor
Joined: Nov 2017
Posts: 105
Likes: 26
From: Delaware
Yesterday I had my oil changed and new battery installed in my 2016 Z51 m7 at a local Chevy dealer. I also them how much to change the transmission fluid and when they quoted $363.00 I declined. My trans shifts ok, a little notchy, but ok. So my question is —is it really a big deal to flush the M7 hydraulic fluid, is there a fluid upgrade, and what’s a fair price?
Safety Car
Joined: Mar 2004
Posts: 4,048
Likes: 1,476
From: South Florida
To make sure fluid is in the differential cooler and lines.
That is a bit high. You can do it yourself if you have the tools. The GM OEM fluid is the best to use and will be about $75 worth of fluid.
Yesterday I had my oil changed and new battery installed in my 2016 Z51 m7 at a local Chevy dealer. I also them how much to change the transmission fluid and when they quoted $363.00 I declined. My trans shifts ok, a little notchy, but ok. So my question is —is it really a big deal to flush the M7 hydraulic fluid, is there a fluid upgrade, and what’s a fair price?
Drifting
Joined: Apr 2018
Posts: 1,323
Likes: 928
From: Burnt Hills NY
I did the recommended minute or two of letting the car run at about 10 mph then rechecking the fluid. Mine did not take any additional fluid. I won't bother with that step next time. Mine is a 2014 Z51.
Tech Contributor
Joined: Oct 1999
Posts: 41,037
Likes: 9,801
From: Charlotte, NC (formerly Endicott, NY)
However, OM also states in the Track Section the Diff Fluid needs to be changed after the very first Track session and then every 24 hours of track usage after that.
Bill
Drifting
Joined: Apr 2018
Posts: 1,323
Likes: 928
From: Burnt Hills NY
I changed mine at 5,000 miles and it looked bad. It had a very silver, shimmery (if that's a word) look to it and also very dark. Most people report the same. It would probably have gone 45,000 miles without a problem but I'm very glad I changed it. Cheap insurance (about an hour of time and the cost of the fluid).