Posted this on another forum, thought it would be good to post here also:

I noticed the brake fluid in the front was looking a little "golden" so I decided to change it. I bought the bike new in Dec 14, so the fluid may have been in the bike more than a year by now. Front was dirty to the point I was surprised at the color and glad I flushed the crap out.

What came out of the rear was really dirty to the point I don't understand why it was so dirty, I mean black, looked like the color of oil that was way past the change interval.

This is not Coke Zero its the mix of front-rear brake fluid.

The input I got on the other forum was this could be caused by contaminated new fluid or the rear rubber line is deteriorating.

* Last updated by: cruderudy on 7/2/2015 @ 11:59 AM *

I was going to guess the rear line. I'd suck the new fluid out in about a month or so and see if it looks black. Mine has always been golden brown but never black. Only black I see is the sediment at the bottom of the reservoir. I've sucked that down a few times without thinking but it never turned the whole batch of fluid black.

* Last updated by: Rook on 7/2/2015 @ 12:50 PM *

Have you seen my bike's stock clutch fluid? It looked like mustard.

weird. The clutch fluid usually gets darker than the brake fluid but opaque like mustard? Is that what we are seeing?

If it looks bad, change it. The "mustard" color is likely a result of moisture contamination. The darker brown colors result from repeated heat cycles. No ides what would turn brake fluid black on a new motorcycle, but get that crap out of there and keep an eye on it.

Vic,

My clutch fluid was the same color as yours after a few months, I changed that as soon as I noticed it was off color. Maybe its the bulk crap they use at the assembly line?

It was mustard colored off the show room floor! Again...anyone that remembers me complaining about having a very tough time shifting when the bike was newer. Changing the clutch fluid fixed that. Although now it's turning black. I just flushed it at 7500 miles (because it was grey/black) and at 9600 it's already grey again in the reservoir. Shifting fine, no functional issues, just turning that odd color.

Maybe I'll try a different brand. I'm just using DOT 4 Synthetic Prestone. Maybe it's not up to the task. It's been fine in my brakes, but maybe it's getting burnt up.

Any suggestions?

Vic,

I was using the Motul 600 boil point in my '06 because I did 4-6 track days. Get it at Cycle Gear, never changed color.

Thanks I'll try that.

It was mustard colored off the show room floor!

Remember, they come here on ships.

My bike has 8500 Km's on and clutch fluid was also a yellowish. I bled that out and as you say Vic my shifting improved. Also installed rear sets last week so had to bleed the back brake, the fluid was black. never had a hassle though with back brakes not working or failing. Flushed the system in any case. Could it not be that new hoses give off a bit of residue that changes the colour?

They all seem to start turning that copper color(yellowish)and I'm guessing it's the heat cycles as was mentioned.IF the fluid is turning black.....I'd begin to suspect the internals of the master(slave)are starting to fail.The rubber parts.Just a guess though.Only ever used the DOT4.Some guys have used dot5...it has a purplish color I do believe.

I can't imagine a black fluid.Only if a guy ran the same fluid for countless miles.Still think it could be the rubber parts deteriorating in there somewhere.Any flecks of black in the res?

Brake lines?yup...didn't think of that.Probably it.

* Last updated by: Grn14 on 7/5/2015 @ 1:43 PM *

Grn,

The rear fluid container seemed a bit off or darker color, that's why I decided to flush it. But certainly not black. I always mop out the fluid in the container with a paper towel and fill with new before I start the flush. The fluid that came out was not only black but did have crap in it. So at this point I'm worried about deteriorating rubber lines and/or piston seals gone bad letting dirt in. Plan is to ride it for ~500 miles and flush again. If it is not clean like new fluid, not sure what I'll do - maybe back to the stealership for a fight on the flaw.

I see Grns point of disintegrating gaskets and such. IME of gaskets or seals deteriorating, the symptoms are usually a little different. For example, maybe there would be small bits of rubber present. It's almost like the brake fluid has been "smoked". It's not black, and there's not chunky particles.

I do ride hard frequently when I get to one of my "tracks" this will include frequent shifting. One thing I've read is turning grey from basically wear of the master cylinder's piston bore, "aluminum micro dust" aka shavings. That scares me a bit. I don't imagine the grade of components are meant for frequent track use. This could be an issue. At the 7500 service this makes sense too because the fluid was basically clear (>good condition) at the slave cylinder, so that rules out contamination from the engine side (like oil contamination or such).

I wouldn't use DOT 5. It's for high performance hydraulics but I've heard it leaks past rubber seals in the 14. I use Valvoline DOT 3 and 4. One product good for DOT 3 or DOT 4 systems. I was told DOT 3 and 4 are now the same thing but DOT 5 has an even higher boiling point than 3 or 4.