Quote Originally Posted by Radical Taz View Post
Question....so how does it get so dirty in a sealed system. There is no carbon due to combustion or clutch fibers or wear material.
Basically...The world isn't perfect! All sealed systems are "open" a little because all matter has holes. The brake systems rubber lines and each connection point allows a tiny amount of air in and the air has a small amount of moisture in it. Over time enough moisture collects to break down the brake fluid and cause rust in the system. The break down process accelerates over time because more moisture in the fluid lowers the boiling point of the brake fluid, which causes more air/moisture in through the rubber lines, and so-on and so-on.