Currently, more than a dozen manufacturers specify periodic brake fluid changes for some, or all, of their models built during the past twelve years. Change intervals vary from as often as every twelve months or 15,000 miles to as infrequently as every 60,000 miles. All brake systems accumulate sludge over some period of time. Flushing the system can remove this sludge and any
moisture, but once you have disturbed the sludge, you want to be sure you get it all out of the system. Stirring up sludge from the master cylinder reservoir may cause it to get into ABS valves and pumps if you do not get it all out of the system.