AtomicZ_Eric

Good even forum members. I'll try to make this brief:

EDIT: Misprint on thread title. Should be TRANSMISSION fluid, not clutch. My apologies.

+ Own a 2008 Z06. Shifts were a bit notchy when trans was cold, yet butter smooth after a couple miles.
+ Changed trans fluid to Mobil 1 ATF synthetic. Nearly 4 quarts came out, yet I only got 3 quarts in. Car was 100% level.
+ Car shifted MUCH better, especially in 1st/2nd when cold. Much smoother when warmed up (better than butter!).
+ Participated in an auto-x.
+ Still felt great.
+ Almost overnight it seemed like the car was became just a bit notchy in every gear, even when the trans was warmed up. Not bad though. Just a very slight "bump" as it was engaging past the synchros. Which was weird b/c that never happened when warmed up.
+ Does this on 90% of shifts.

Potential Causes that I can think up:
1) Most people have stated that they get about 3.25--> 3.5 qts in when changing the trans fluid, whereas I only got in 3. Maybe the residual GM fluid is foaming?
2) When diluting clutch fluid via Ranger method maybe a couple air bubble got in the line from the fluid squirting in the resevoir, and therefore clutch doesn't disengage entirely? I don't think this is the case as the friction point seems a normal distance away from the bottom of the clutch travel.
3) Air pockets formed in the trans during the fluid change b/c I didn't rotate the wheels while it was in gear, potentially preventing a proper amount of fluid making its way in.

Again, to be clear... Almost over night it seemed as thought shifting b/w gears became kinda notchy. By that I mean that there is just a tiny "bump" as I'm about halfway through engaging the next gear.

I'm thinking of changing fluid again (have 2 auto-x's under my belt) and tilting the car to get 3.5 quarts in. Any thoughts / advice would be appreciated. Thanks in advance.

X25

It states 4.2 quarts for GS, and 4.5 quarts for Z06 and ZR1 in the capacities section of the '10 and '12 user manual.

One idea: if you run the transmission a little bit after the oil change and check the level, perhaps it will let you put in more? I know that the differential requires you to turn the wheels at 10 MPH for 1 minute after the fluid change and re-check the level, which, usually shows low afterwards.

Kiser64

Did you check the fluid level after you ran the Z? Sounds like you might have emptied the cooler and lines, but not gotten the new fluid back into them. I have also heard on here of some low mileage cars having synchro issues that led to transmission rebuild/change. Is she still under warranty? Good luck with it...

AtomicZ_Eric

I think you guys may have nailed it. It never occurred to me that I got all the fluid out of the cooling lines! I planed to change fluid again, just to be safe. But now I will make sure to check the level after I drive it a couple miles to verify the level hasn't gone down due to the extra fluid in the cooling lines.

Thanks a lot!!!!!!

There is no tutorial / write-up that I've seen mention this step. I'm just hoping I didn't damage the trans with the low level :-/ It's CPO so I think I have another year or two with the powertrain warranty.