Edmunds Answers



  • karjunkie 04/13/10 2:50 pm PST

    First off all DOT3,4 and 5.1 brake fluid is synthetic (polyglycol and glycol ethers). I believe your question is about silicone based brake fluids (DOT5) that are not hygroscopic and do not absorb moisture. Yes you can convert to a silicone based fluid, but it requires a complete flush of any existing fluid as it is completely incompatible with other brake fluids and really is not necessary. Silicone based fluid is mainly used by racers because it has a higher boiling point. It is quite easy to flush the brake system with good old regular DOT3 brake fluid and flushing of the brake system should be done every 2-3 years anyway to rid the system of impurities that develop from the components.

  • colin_l 04/13/10 4:39 pm PST

    By the time you need DOT 5 brake fluid, you're a professional racer. The boiling point of modern DOT4 fluids is fantastically high, and you don't even have to spend a lot of money on it. Valvoline SynPower is a very high performance brake fluid found at any autoparts store or Wal-Mart.

    I have used it on the track. :)

    Anyway, if you bleed your brakes every 1-2 years using good quality NEW brake fluid you won't have any problems. Because of the water absorption, it's a bad idea to re-use an old container you might have in the garage. Most brake systems have less than 16oz total capacity and you'll use maybe half that at most when bleeding.


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