KnightmareCS

That's motor oil.
No questions there, use whatever motor oil that meets spec.
Diff is different since there are specific friction modifiers. Base stocks can be the same between Mobil1 and GM, but my assumption is that each has their own specific additives. Figure Mobil1 is going into ANYTHING while the GM stuff is going into GM specific diffs. Now whether that means Mobil1 has 5% of one additive while the GM stuff has 6% of it I don't know, but that's pretty much my logic.
And I used to work for an OE power transmission fluid (think autos/DCTs/CVTs) developer/supplier. Now THOSE things are picky...

v8sten

I just picked up my GM diff fluid the other day and now im waiting on the trans fluid to come in so i can change it all at once (motor, trans, diff). being new to the corvette world, this tread has helped out a lot.

Boxcar

I was just doing a little research after reading all the "chatter" in this thread. I couldn't find any thing real specific about the differential. but, I will be going by the dealership to get the clips to have on hand and I do believe I'll go with the GM fluids and return the 'questionable unknowns".

I just hope the Corvette tax isn't to hefty.

To: v8sten, that is what I'm going to do, the engine, trans, dif, clutch, brakes, and coolant. Just hoping it warms up a bit.

1972bluelt1

You can shop on line and usually get a better price than the dealership. I think I got mine from gmpartsdirect.

Mookster

Any of you tried Amsoil Severe Gear® 75W-90
http://www.amsoil.com/shop/by-produc...?code=SVGQT-EA

With Slip Lock Gear Oil Additive over GM oil?
http://www.amsoil.com/shop/by-produc...?code=ADATB-EA

Also, is this still the latest GM Part #88862624 ?

Thx

Jcbarr25

This is what my dealership recommended and used on my differential. I also change the teanny fluid the same time. A total of like 200 out the door. Would have done it myself but I had no time

Mookster

What did they recommend? Amsoil or GM/AC Delco fluid?

Jcbarr25

Amsoil.

Vito.A

GM Part #88862624 is $22.31 per quart on Amazon.

jimbob8915

It is even cheaper on ebay but me being of the type that needs instant gratification an decided to change my diff fluid today I paid $26 a quart at my local stealership.

1972bluelt1

$13.94 at GM Parts Direct. Didn't check shipping. Seems like it wasn't that bad. Some times they rip your head off. Best deal I ever got was on Ebay, but couldn't find it when I needed more.

crAzy

So I went and had my rear diff fluid changed. Noticed the fluid was quite new. Guess the previous owner changed it without telling me. I put 30K miles on it since owning my C6 Z06. Anyways after it was done I did the "wheels off ground and start car" procedure. I guess the mechanic possibly forgot to top it off. So moving on with my problem I noticed a humming/whine noise (I think) when driving around the 40mph+ range. I then would notice if there was a slight turn in the road that slanted right it stop that humming/whine. So all the weight would be on the driver side. When I straighten back out the noise comes back. The noise is similar to large truck tires driving down the road, btw. So yesterday I go to check and make sure the guy topped off my fluid thinking it may have been low. So I go and jack up my car a bit staggered. Undo the fill plug and then fluid starts coming out quite a bit. I was confused. SO I let it drain out till it stopped. Put the fill plug back on and then went on my way. The noise is still there and still goes away when I veer to the right and reduce weight on the passenger side.

What do you guys think could be the problem? I do need to go in and fix my alignment as it is still pulling to the right some and was going to do that this weekend. Since they have a drive on machine I was going to double check the fluid level as the car will be sitting on a flat surface.

LS3_Beast

Great write up, changed my transmission fluid and differential fluid with your DIY in about an hour... HOWEVER... The little infamous Clip... You said to put it in and push towards the front of the car... Mine was opposite, after fighting with it for about 20 mins trying to put it on and push it towards the front like you said, I switched it up and put it to where I had to push towards the rear of the car and it went right in. Took 1 second. Just throwing this in so others won't sit there trying to force the clip to go in one way, possibly damaging it. It can go in any way. Just put your head up in there and look where then holes/indents are on the differential and just match the clip and push it in. Great job OP! Thank you!

LS3_Beast

Did you ask what kind of fluid they put in? If it wasn't GM did they add the additive? That's probably what's causing that infamous whining/humming noise.

Fabio-Z06

Great write up!m thank you for going thru the trouble for us.

MickVette

Does anyone have the part number for that little clip handy?

1972bluelt1

24205103

GA$$MAN

I'll finally get around to doing this this weekend! Hopefully the rain holds off because my garage is too small and cluttered.

Orpheuss

Hey guys I’m new to the forum but not new to corvettes. I just bought a 06 Z06 and did a full fluid flush of pretty much every fluid except for my coolant. I took it to my buddies shop last night since he works at a dealership and has all the tools. I used Valvoline 75-90 rear gear oil and Mobil sythetic ATF for trans. I now have a leak on the bottom of the car. My concern is that the leak isn’t small and I drove it to work today and am worried that it is either from the rear dif drain plug or trans fill plug. I did all the steps for the diff and trans but I am concerned that since my car is low mileage (25k) that the trans plug sealant from factory might not have a tight seal. I daily this car and would like any recommendations?

Ohh and I was wondering if my fluid choices were good or I should drain both trans and rear diff fluids for factory? Will my trans burn up? Btw all the fluids were from factory and never changed once in 14 years that’s why I did the change my self to know when I need to do it again.

Dirty Howie

I have always used the GM fluids and never had an issue.


DH