car2fast4you

There has been some hype around The Forum lately about unusually dark clutch fluid.

I don't mean to start any wars, or bash any other forum members here.
I simply want to make sure that I am taking the best possible car of my Vette, and that I am not making any mistakes by doing things myself.

A prominent CF member has recommended that you keep the clutch fluid clean by changing it via the fluid reservoir.
I did this & found that the fluid starts to become dark again after only a week.
So, the more I think about it, the more I wonder if doing this makes any sense at all.

Now, I do some of the maintenance on my car myself. But changing fluids & filters is about the limit of my expertise.
I'll leave everything else to the experts.

While poking around on another forum, I stumbled on this GM TSB.
It seems to imply that the LAST THING you want to do is open the clutch fluid reservoir.
Simply put, GM recommends leaving the fluid alone & properly changing it every 2 years.

I know that there are several Corvette service & repair experts on this forum.
I'd like to here from some of them regarding this issue.

Thanks in advance.
I apologize if I've ruffled any feathers here.

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07-07-31-001A: Clutch Hydraulic System - New Service/Owner Maintenance Information - (Sep 11, 2008)

Subject: Clutch Hydraulic System -- New Service/Owner Maintenance Information

Models: 2005-2009 Chevrolet Corvette (Including Z06 and ZR1) with Tremec 6-Speed Manual Transmission (RPOs MM6, MZ6, MH3)

This bulletin is being revised to update the models to 2009. Please discard Corporate Bulletin Number 07-07-31-001 (Section 07 -- Transmission).

This bulletin is being issued to provide dealers with additional information on servicing the clutch hydraulic system.

Please also advise customers of this new maintenance information.

Some cases have been found where the vehicle's clutch hydraulic system was contaminated with water.
Higher than expected levels of water in the clutch fluid greater than 2% may cause the clutch fluid to boil.
The presence of water in the fluid lowers the boiling point significantly; when this occurs, the driver may lose customary clutch pedal feel and performance.

To eliminate the opportunity for moisture to enter the clutch hydraulic system:

• The clutch fluid level inspection should be a VISUAL inspection only.
Look through the transparent reservoir and observe the fluid level.

Avoid removing the cap !
DO NOT remove the cap just to top-off clutch fluid. Leave the system closed and sealed.

During PDI inspection or routine service, the cap should not be opened for just an inspection.

• Open containers of DOT 4 clutch fluid have a two week shelf life.

DO NOT use fluid if the container opening date is unknown or older than two weeks. DO NOT mix or re-use old fluid. Current service information already covers the issue of reuse.

• To provide the best clutch operation, it is recommended that the owner change the clutch fluid every two years.

Please flush and replace with P/N 88958860 (P/N 88901244 in Canada) or equivalent DOT 4.

talon90

Contaminated fluid is always dark. Dark fluid is not always contaminated. I've been saying this on the forum for years. There are components of the clutch system that when these materials come in contact with the fluid will discolor the fluid. You can get your fluid crystal clear and within a week or two it will likely come back dark. If you do it enough (and I mean a lot), you may in fact purge most of the materials that cause the fluid to change color but eventually, it will still over time come back dark. Now, those that race and are otherwise punishing on the clutch should likely consider changing the fluid more frequently. Those that don't are wasting their time and money in addition to simply changing the fluid in a seldom used Corvette because it is dark is just not necessary.

RUBYREDVET

Good to know. I was just about to get a syringe and fluid to change mine. '08 Z06 purchased last August. Looked at the fluid last night after reading about changing it. It was dark. Since it's normal, I'll leave it alone for a while longer.

GotVett?

. . . as I just changed mine out, yet again, today.

retaf87

The info in the GM bulletin pretty much confirms what I was told by the local Corvette shop and the dealer. Fluid will get dark quickly, but that does not mean it is no longer doing its job.

S2K

If you have problems with the cluch sticking then try the Ranger method to see if it goes away. If you do not, you don't need to do anything. I've had the same fluid for over 50k miles and just recently did the Ranger method just to try it. No difference for me, but I also did not have the clutch sticking problem.

At the end of the day you really don't need to create a problem where there isn't one. So again if your clutch doesn't stick, don't worry about it.

edved

Some good advice stated. I'll discard the fluid if it's greater than 2 weeks old, but I'm still gonna routinely replace the dirty fluid for my peace of mind.

lander

The key decision for me was that I could see water droplets in with my clutch fluid (At least I assume they were water droplets as they were not mixing with the clutch fluid). Because of that I've changed mine out several times until I'm satisfied the contaminating fluid is no longer present in my clutch system.

Since I immediately put the cap on as soon as I've refilled the reservoir, I'm not concerned with the atmosphere contaminating the fluid.

hawkgfr

Funny...I could see the water in mine the first time I changed it...at 3k miles...(that really good GM stuff )I now change it at least every oil change and it is not only void of water it shifts better too.

As for opened containers having a two week shelf life...that may be true IF you leave the cap off. What a bunch of poo...lol

VettedCandidate

I did the changeover a year ago for the first time because my car is an '05 and I wanted it clean and for it to be the new DOT 4 fluid. I did notice a better, smoother clutch action. I have since done it once or twice just because. The question I have asked several times and have never really gotten an answer to was what is this really helping? I know that the clutch dust is supposedly bad for the seals but, is that the only real benefit?

Daytona Bob

Search Ranger's posts...typically this helps with consistent pedal pressure...in some cases racing applications the clutch could stay on the floor.

I like what Talon90 has said...

CMY SIX

what! the motor oil never changes color?

GMautotech

The dark color comes from the dye in the o-rings of the hydraulic system.

ron-z51

There is no "Dye" in the o-rings. It's carbon black, a key component in nitrile butadiene rubber. If it's coming out of the seal than the seal is either wearing or dissolving.

MarkRx

i think heat has a tad bit to do with it... i also believe it can be darker than normal, just make sure it's around the 3/4 mark or above and you're fine. Night and day difference when i used the ranger method. it came from the factory bout 1/3 full. from day one in my new 08 with 3 miles it felt like the clutch had intermitting chatter. i did theranger method and made sure it was topped off and it shifted alot smoother. this may not make sense, but it shifted easier into 2nd gear before it was fully warmed up, another gripe about the TR6060 tranny. It felt like a whole new car so i was very happy

LT1 Z51

Two week shelf life? That's almost laughable, I bet these are the same people telling me my Printer ink "expires"

Fluids in properly sealed containers (with caps on fully) usually take YEARS if not longer to go bad.

car2fast4you

Paul, thanks for the feedback.
Your voice of infinite wisdom & abundant Corvette knowledge is one that I trust.

Thanks to the others that responded as well.

This is a somewhat "dark & murky" subject......and not everyone is going to share the same opinion.

hawkgfr

I agree...but the proof is in the pudding...change yours out and you will FEEL the difference.....

car2fast4you

I DID change mine out.

I haven't felt any difference.
It still shifts a little rough between 1st-2nd, and 2nd-3rd, until it gets warmed up.
Once it's warmed up, it shifts smoothly, like it always has.

From now on, I'm going to follow GM's recommendations.
I'll have the clutch fluid properly changed every 2 years.
I'm convinced doing otherwise is a waste of time.

torquetube

This is standard operating procedure. They want to discourage repeated removal of the cap (especially on cold, foggy nights). That said, the only way to get fluid in the system is via the reservoir, and if you're opening it to suck out the old and pour in the new then the net water content in the system will be going down, not up.