Brake Fluid ?
Instructor
Joined: Feb 2010
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From: KY
Team Owner
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From: Lacey WA RVN 68-69
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You can mix DOT3 and DOT4 with no real problems. Hard to say if all DOT4 fluid is synthetic; depends on the manufacturer.
What sort of driving will you be doing? The DOT numeric value deals with ranges of wet and dry boiling points. DOT3 fluids will have boiling point up to around 310 degrees wet and 450 degrees dry. DOT4 boiling points can be up to around 350 degrees wet and 500 degrees dry
DOT5 fluids are silicone based and should not be used at all in cars with ABS systems. There is a DOT5.1 that has even higher boiling points.
For street driving, a DOT3 fluid will work fine and it can even be used for autocross events. For an occasional track day or high speed autocross, an upgrade to a DOT4 fluid would be a good move.
Of course as the boiling points climb, so do prices. The ATE Super Blue runs about $12 per quart. Get into SRF and Motul 600 and the prices will be higher.
What sort of driving will you be doing? The DOT numeric value deals with ranges of wet and dry boiling points. DOT3 fluids will have boiling point up to around 310 degrees wet and 450 degrees dry. DOT4 boiling points can be up to around 350 degrees wet and 500 degrees dry
DOT5 fluids are silicone based and should not be used at all in cars with ABS systems. There is a DOT5.1 that has even higher boiling points.
For street driving, a DOT3 fluid will work fine and it can even be used for autocross events. For an occasional track day or high speed autocross, an upgrade to a DOT4 fluid would be a good move.
Of course as the boiling points climb, so do prices. The ATE Super Blue runs about $12 per quart. Get into SRF and Motul 600 and the prices will be higher.
Instructor
Joined: Feb 2010
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From: KY
Yes as far as I am aware Dot 4 is synthetic, and that brand I use says on the bottle that its ok to mix. However I would drain your system, clean out the reservoir and run the new through until it is bright blue (or what ever color it happens to be.
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The Ford Motorcraft brake fluid used to be the best cheap brake fluid with a much higher boiling point, but I heard the latest stuff is about the same as parts store fluid.
That said, I use parts store fluid for the street. it doesn't absorb moisture as much as the race types. The way I figure is that I can always bleed it out before a track day with the good stuff, but store bought is formulated to be ok for longer periods of time if you don't get a chance to change it every six months or more.
That said, I use parts store fluid for the street. it doesn't absorb moisture as much as the race types. The way I figure is that I can always bleed it out before a track day with the good stuff, but store bought is formulated to be ok for longer periods of time if you don't get a chance to change it every six months or more.
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Melting Slicks
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From: Northeast FL
Street car or race car? There's a difference in "best" depending on what your intent is.
Street car fluids don't typically have to endure sustained high temps. And they are more resistant to absorbing moisture over time. And they're easily available and very cheap.
Fluid intended for a race car has higher wet and dry boiling points but the tradeoff is that they are more likely to absorb moisture out of the air quicker. Race cars don't worry about the moisture because most of them get the fluid flushed on a regular basis whereas a typical street car doesn't get the fluid flushed very often, if ever.
I use Motul because I boiled the Valvoline synthetic regularly and I can't afford SRF.
Street car fluids don't typically have to endure sustained high temps. And they are more resistant to absorbing moisture over time. And they're easily available and very cheap.
Fluid intended for a race car has higher wet and dry boiling points but the tradeoff is that they are more likely to absorb moisture out of the air quicker. Race cars don't worry about the moisture because most of them get the fluid flushed on a regular basis whereas a typical street car doesn't get the fluid flushed very often, if ever.
I use Motul because I boiled the Valvoline synthetic regularly and I can't afford SRF.
