That would be factory fork oil that's 5 years old! I had a day off to burn and decided to replace my fork oil. No drain plugs on my 06 so pulled the tubes off. Inverted the tube in a 5 gallon bucket and the fluid started coming out. First was somewhat clear followed by yellow. I started pumping the tube and everything after that was black. Pretty nasty looking. I added fresh ATF and pumped and drained a few times until it was a consistent color. I then added ATF and closed it up. If you have not changed your fluid its really pretty simple and should be on your "to do" list. Cheap and easy is a good thing!