RE: Re: My brake job advice & brake fluids <long>

["Gilbert, Clark" <Clark_Gilbert@xxxxxxx>]

What I know about brake fluids - not much actually:

DOT 3 - boiling point 401 degrees F dry. 3% moisture will drop this to
301 F
DOT 4 - boiling point 446 F, 2% moisture will drop this to 246 F
DOT 5 - boiling point 500 F, will not absorb moisture. Likes teflon and
stainless brake lines. Little lubricating qualities.

DOT 3 and 4 are glycol based, hence hygroscopic. DOT 5 is silicone
based. DOT 3 and 4 have about 5% dissolved air. DOT 5 will accept up to
15% dissolved air. That is what prompts the stories of stuck brake
systems. This is also what makes it incompatible with ABS systems. I do
not know why.

DOT 4 will absorb water at a slower rate than DOT 3, but the effects are
greater, as you can see above.

My $0.02, adjusted for inflation.

Clark

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