dark clutch fluid
 

last year I put in a new clutch, slave cylinder, flex line and OEM master cylinder. Bench bled the unit with it in the car then I use my vacuum bleeder to clear the whole line and re-filled with fresh Motul RBF600. I put about 10,000Km (6,000 miles) on it since. No air in there, pedal feel is great and all good. I just checked my fluid and it's already dark. Could it be the rubber hose between the reservoir and master cylinder? I had cleaned that puppy pretty good even running clean cloth trough it before reinstall. I used thee vacula, emptied out the reservoir , wiped the interior down, re-filled (repeated the process) lets see what happens.

Yes, the black rubber hose attached to the master cylinder breaks down and contaminates the fluid. Mike Upton (on FB) sells a clear hose that replaces it.

Is there a link to this Mike Upton? tried on FB but oodles of Mike Upton on there and nothing cpecific to 370Z or parts. Or for annyone that sells alternatives?

It does it. I just gravity bleed mine whenever it needs it when I am doing an oil change.

Here is his profile:

https://www.facebook.com/fillemuptown

To my knowledge, he's the only one that's ever sold it (which is surprising the way Z1 copies other people's work).

But, I've had mine since 2020 and have only changed the clutch fluid during my winter maintenance, but it's always clean (relatively speaking, of course).