Document ID# 1990151
2008 Chevrolet Corvette

Subject: Clutch Hydraulic System - New Service/Owner Maintenance Information #07-07-31-001 - (06/19/2007)

Models: 2005-2008 Chevrolet Corvette (Including Z06)

with Tremec 6-Speed Manual Transmission (RPOs MM6, MZ6)

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.

I found a electronic test tool that you simply put into brake fluid and it tests the fluid quality.
It has 3 LEDs of Green, Yellow and Red so you know if the fluid really needs replacing or not.

As in this case the fluid was never used, in a colored bottle and still was degrading once the cap was taken off.

How often would you recommend testing? I still run the original brake fluid and the car is 5 years old. Other racers that have driven my car are amazed at how well it stops relative to their own Corvette. I only have Goodridge braided SS brake lines and Hawk Plus brake pads...the rest is stock.

If car is not doing heavy duty racing then heck once a year would be just fine.
If doing lots of hard braking then i'd check few times a year.

I tested both my 1999 car and pickup, pickup I have never changed the brake fluid and it still tested just fine.

Vette I may have changed brake fluid once for brakes and twice for clutch and it also tests out just fine.

Point is the cyberspace fad for vettes is somehow if you change the fluid for clutch every month that somehow it will prevent clutch problems is bullshit and only causes people to open cap of master often and allowing water vapor getting in and that is what kills the fluid.