REFLECTOR: DOT 5 Compatability

[John Dibble]

Hmmm.   My Velocity had the amber color fluid in the brake system when I
bought it.  I asked why the fresh  bottle of DOT 5 that I bought was
purple.  I was told that it changes color (to amber) if it is exposed to
water.  So I have been adding DOT 5 to my system as make up.  When I get
back home I'm going to take a sample of what's in the system and see if
it mixes with water.

John

Wayne wrote:

> Now I'm even more confused. I just looked at my bottle of NAPA DOT 5
> silicone brake fluid. It is amber.
>
>      *DOT 5:* This brake fluid has a silicone base. It is purple
>      in color. It is
>      NOT hygroscopic (meaning it cannot and will not moisture)
>      and has a minimum
>      dry boiling point of 500°F (260°C) and a minimum wet boiling
>      point of 356°
>      (180°C) It is not used in many brake applications, seeing
>      primary duty in
>      weekend, antique, and collector cars that sit for long
>      periods and are never
>      driven far. It does not mix with DOT 3, DOT 4, or DOT 5.1.
>      It will not
>      absorb water and will not damage the paint on a vehicle. It
>      is also
>      compatible with the same rubber formulations as the DOT 3, 4
>      & 5.1 fluids.
>      The problem with it is that it can easily get air bubbles
>      into the system.
>      The air bubbles are nearly impossible to remove and result
>      in poor system
>      performance and poor pedal feel. Although originally
>      developed in the late
>      1960's by General Electric specifically for racing, it is
>      unsuitable for
>      racing for a variety of reasons. (Scroll to the bottom for
>      the scoop on
>      Silicone) If as little as one drop of water enters the
>      fluid, severe
>      localized corrosion, freezing, or vapor lock may occur. This
>      can happen
>      because water is heavier and not mixable with silicone
>      fluids. It is
>      unsuitable for ABS.
>
>      *DOT 5.1:* This brake fluid is similar to DOT 4 it has a
>      base comprised
>      primarily of Borate Ester. Often in the range of 70 - 80%.
>      To meet
>      specification, it also will contain other additives. It is
>      clear to amber in
>      color. It is hygroscopic (meaning it absorbs moisture) and
>      has a minimum dry
>      boiling point of 500°F (260°C) and a minimum wet boiling
>      point of 356°F
>      (180°C) minimum. It is almost exclusive to Europe, used in
>      high performance
>      cars. It can be mixed with DOT 3 or DOT 4 without damage to
>      the system. It
>      maintains higher boiling point than DOT 3 or DOT 4 fluids
>      due to its even
>      greater borate ester content. It is excellent for severe
>      duty and racing
>      applications. The problem with it is that it costs more than
>      other fluids
>      and there is limited availability in the USA. It also
>      absorbs moisture out
>      of the air and thereby reduces its boiling point. It can
>      also damage the
>      paint on a vehicle.
>
>
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