Brake fluid certainly darkens with age but usually a dark brown colour, not black. The clutch fluid on my previous bikes, a 900SS and an ST4s used to turn black but I found that over the winter when the bike wasn't being used it would settle to the bottom of the reservoir like a fine powder leaving the fluid clear or at least honey coloured. So I think, yes there is some contamination from seals/brake lines whatever. Once the black had settled I would empty the reservoir with a syringe, wipe out all the sediment with a paper towel, then refill it with fresh fluid and bleed the system to flush it. On the MTS I'm currently using Racetech DOT 5.1 in the brake and clutch systems. It's been in there about 5 months and 4,000 miles and is showing no sign of turning black yet. Rear brake is still crap though
He's using the new "Stealth"(TM) brake/clutch fluid. Available from all good customising shops at £9.99 per litre.
As I said up there ^^ my Hyper fluid went black so I changed it for Shell and it's never done it since. No other changes - hoses, reservoir pipe, etc - and it stays clear. Same for brake fluid. It must be the oem fluid they use reacting with something!
