Is replacing only the brake fluid in the fluid reservoir good enough or must I have a mechanic do a whole system fluid flush? I don't have any braking issues and the fluid looks fine, but it has been about 5 years and 50,000 miles since it was last replaced.
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2001 Volkswagen Passat
Question: Brake fluid exchange
Answer #1roman from Roman's Auto Center, March 13, 2011, 14:20Enthusiast
yuors life depend on good brakes can you afford
Answer #2raiderron March 13, 2011, 14:23Master
Depends on mileage, the reason it is recommended is that brake fluid is vented to the air because it expands when heated during brake operation, because is vented it will absorb moisture from the air and then the boiling point will lower and can cause brake fade especially when coming down a pass and may be riding the brakes and not letting them cool down. Loss of pedal pressure in this instance can be frightening. Moisture inside the brake fluid can accelerate the brakedown of internals in the brake system. Fluid may still look good but that is why it is recommended so brake system has a chance to remain in top shape. I personally feel the most important system on any vehicle is the brakes. But of course it is your call. By the way, if you use synthetic brake fluid it does not absorb moisture.
ReplyRob, March 13, 2011, 15:22Rookie
Thank you for your response. It sounds like you are saying it is probably not enough to only replace the fluid in the reservoir.
Answer #3patrick mannion from Greg Solow's Engine Room, March 13, 2011, 15:42Master
Agree with Raderron's great answer. Flushing the brake hydraulics is very important part of maintaining brake system health. I like to suction bleed the brakes rather than replacing the brake fluid by having someone "pump" the brake pedal. But and this is important do not use synthetic DOT 5 brake fluid in your car particularly if it has ABS brakes. Use a good name brake DOT 3 or 4 fluid.
Replyraiderron, March 13, 2011, 17:44Master
Patrick, this is raiderron, When did the "do not use" synthetic fluid with ABS come into play. Been long enough since in a shop environment that I have not heard about this. Any info is appreciated.
Replyoverbys, March 14, 2011, 09:29Master
the VW Passat specifies DOT4 brake fluid only; using any
fluid other than this means that the installer knows more
than the manufacturer and is current with his garage liability insurance.