The first two were rebuilt, the third was a brand new raybestos. I use clean fluid, and since the system is so short, it ends up flushing it every time I bleed the lines. This last time it leaked, the fluid was very thick, and almost gray in color.
If the cylinder is brand new, the seals should be good (I know a master brake cylinder that has sat on a shelf can go have seals that go bad, but this clutch cylinder worked fine for about 5-6 months, so I don't think that is it)
I don't know if this is true, but I've heard that the pedals can go, and cause the rod to go in crooked, over time, it wears out the cylinder. Any one know if that is a genuine cause?