In the past, I will usually change brake, clutch, anti-freeze fluids every 2-3 years. Well here is a sample of two year old brake line fluid and the clutch was just as bad with trash in the fluid as well.

From the looks of this fluid, I may start changing the DOT4 fluids every year. I hope this was a bad batch of fluid I used two years ago and not a sign of line problems since I run new fluid through the lines until it is clear again when I change the DOT4 fluids.