| clutch Fluid
Thanks for the link Shazaam!, very interesting thread.
In my case the fluid is certainly not the factory stuff, as it is a 1997 bike, and I replaced all the fluids before putting it on the road, and changed it again when I relaced the seal. Looking at the master cylinder resevoir the discolouration is caused by foreign bodies in the fluid which settle on the bottom of the resevoir. The new fluid has been in for about 10 days and 400ish miles. I use DOT4 fluid
The particles could easily be rubber fron the seal or the O ring, or dirt working its way past the seal in the slave cylinder | 
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