How often should brake fluid be replaced in a Subaru Impreza 2002? Or should it be replaced at all?
(Looking for distances in km)
Subaru recommends every 48000 km or 30 months. It also recommends that it be changed more often if used in severe conditions. Severe duty would be lots of stop and go use like a taxi would see. Or very dusty conditions, wet conditions, towing heavy loads etc. The reason for the flush and change is because brake fluid absorbs water and water promotes rust. There are also additives in the brake fluid that weaken over time. The Antilock Brake (ABS) system consists of valves, pumps and solenoids that have very small passages that can get blocked by small pieces of rust and dirt. If blocked the system may not work correctly. Way back before ABS cars had a simpler fluid transfer system. The ports were large enough that they didn't clog as easily and with most American cars the lines rusted through and the fluid was replaced with the new brake line. You may be able to get away without flushing the system for many years but may also wind up with very expensive repairs.