davidfarmer

I realize this is an older post, but one piece of advice. If you load the rear suspension when you "drive car" it will be much more stable. The halfshafts are at a steeper angle at full droop than at normal load, and it causes a lot of clunking and vibration.

Normally I have the wheels off when I do this service anyway, but even loading the control arms slightly (with wheels still on) can help a lot.

Mpwr

Great write up!! I just got my car with 8,500 miles and this has not been done. Im going to be doing this soon.

Dreamin

How funny... I was just reading this post today to get the fluid P/N... time for fluid change #3 for me. And i'm getting the old fluid analyzed

Silver05GTO

Just did mine this past weekend with your thread

How long does your diff stay quiet? I had CoW change the fluid out 2 months ago and the noise came back within a few thousand miles. I drive much more then the average Z06 owner so at this rate i'll be doing 2 diff fluid swaps per 1 oil change!!

KodiaknMe

Dreamin

I change diff fluid every 6-8 track events... not because of noise.
I had my diff fluid changed to the new stuff by a dealer when the car was new because I had pretty bad chatter, but no noise since then (~24K miles)

Silver05GTO

Interesting. I've had 2 C6's and both chattered, noise came back after each fluid change within 5K miles. Both times fluid change was done at CoW, both times I hit the highway after for about a 2 hr drive home. Wonder if not doing the circles/figure eights right away shortened the life of the fluid or something?

It's deffinatly the fluid breaking down, I tried doing figure eights when they started chattering and it didn't help, only thing that quiets it is a fluid drain and refill. This time after I changed the fluid I went and did figure eights to work it in.....hope it lasts this time around.

Cor Dame

Hi,

I read somewhere on the forum that the zo6 that went to europe need more oil in the diff than the us models.

I have just put the new gearbox oil in and now i want to do the diff.
I only have 3 bottles so now i am afraid that i dont have enough diff oil.

Can somebody helpe me out?

Grtz, Hans

Mpwr

Buy an extra bottle and start filling till you get slight over flow. Allow overflow to drain then cap it. Drive the car and recheck level.

Gearhead Jim

BTW, my 2009 Service Manual says the "start it in the air and use 2nd gear" thing is only for the cars with a differential cooler. I presume that means Z06 and ZR1, and maybe the new GS with manual tranny.

jan eric

Thank you Dreamin. dvandentop, if you ever find that clip I am sure you will find all the parts I have ever "lost". Please send them to me . I will reimburse you for up to $200 in UPS fees. Because of your post(and of course dreamin's) I was very careful with the clip.

peterpiper

3 hours, and I still have the figure skating to do! Thank you, dreamin ... you helped me be an "expert" the first time around! It would have been 2 hours if I had smaller hands and knew how the clip clipped! -pp

08zee

Okay, so I learned that you better have a lot of patience and a sense of humor to do this procedure. After losing the clip 7 times and having to reshape it at least as many, I finally saw the humor in such a situation. The clip was put on at the factory from passenger side toward driver's side. So, that's how I took it off (that is, pushed it toward the passenger side). This was all easy, until I finished draining the gear oil. I had already changed the engine oil and oil filter and changed the tranny fluid. But, once I started trying to put the differential drain clip back on I initially tried from the passenger side to the driver's side (since that's the way I found it), then from the driver's side to the passenger side. 3 1/2 hours and 7 lost clips later (though I found the clip each time until the 7th, when I had to call in my wife who found it up above in the vette's suspension where only a small hand could go) I finally decided to try a different procedure since calling on the Pope and every saint I could think of didn't seem to be working. And, in 8 seconds flat I had installed the clip from the rear towards the front. As they say, even a blind hog finds an acorn every now and then and I finally got the job done. Although, I wouldn't mind having a word with that factory worker that put the clip on from passenger side to driver's side instead of from rear to front. And I think I've decided that the differential gear oil probably doesn't need to be changed after every 5 track days.

the_teapot

Great write-up Dreamin! Kudos to you for such a detailed post. I did the diff fluid change on Friday and thanks to this thread it went great! As everyone else, I enjoyed wrestling with the retention clip but otherwise it was a fairly simple maintenance job. Thanks again Dreamin!

A-Z

After 3,100 miles (total odo) on my '09 Z06, including five track days, I changed my diff fluid last night. First, thanks to the OP and Roger ("4 wheels") for guidance. Here are some further observations from my experience.

I decided to drain the lube into a clean white bucket to get a better idea of how the fluid looked. Photos attached. (Why do some pics upload full size to the body of the post, others as little "piclets"?) I also decided to strain the fluid to see if there were any larger metal shavings/fragments. I used a medium mesh paint strainer cone because that's what I had on hand. No metal shavings/fragments detected.

Quantity: my car took almost all of three quarts plus a 4 oz. tube of LSD additive. (What I call Roger's Amsoil Mix: 1 qt. Severe Gear 75w-110, 2 qts. Severe Gear 75w-90, 1 tube Slip Lock Additive. BTW, I used the Amsoil hand pump and it worked well.)

The clip locks onto the fitting in three slots, not two, which is helpful to know when positioning it for reseating. (Can someone explain to me how this type of fitting seals without compression or an o-ring?)

As noted by others: the clips are elusive devils if you drop one, especially if you are working from standing height under a lift, as I was. They bounce and are very hard to see on a concrete floor. (I had to sweep my entire shop floor twice to find the clip.) Have an extra on hand in the event you lose one.

The jerky movements complained of by others when running the car in the air is due to the traction control braking the wheels and cutting the throttle in response to your attempts to accelerate. Deactivate the TC and the wheels will spin smoothly. (Took me a while to figure this out.)

Anyone know what the ingredient is that makes the diff lube have that unusual, unique smell?

Andy

Neverdone

A great way to find your level is to get a plastic zip tie, bend the tip 90* and simply dip it the hole.

6spdg37s

what milage intervals would you recommend doing this at ? I have 6k (total) on my odo.. 3k from me and 3k from previous owner.. car is gm certified

Snake.Oiler

I haven't changed the diff oil on my vette yet, but I change my truck every 15,000 miles.

Of course, if your track the car, you would want to do it after every X events

LMBZ4ME

Thank you Dreamin. I did this procedure last weekend and the only problem I had was getting that clip back into place. I was a bit surprised that only about 1.75 quarts drained out. Not sure why the fluid level was so low. I was able to get almost 3 quarts pumped back in upon filling.

RoHo

Wow!! so are you saying you were over a quart LOW?

Damn, I think I will change mine this weekend to be sure it's up to snuff.