BRAKE FLUID

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Dec 16, 2012
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Oregon coast
I believe the fluids themselves are completely compatible, and the materials on the system would ne compatible with DOT 3, but dot 4 has a higher boiling point. This would make me think that you system runs too hot for DOT 3 FLUID. In short, don't do it. There is no advantage at all to DOT 3.
 
Joined
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Oconomowoc Wi
Originally Posted By: asand1
I believe the fluids themselves are completely compatible, and the materials on the system would ne compatible with DOT 3, but dot 4 has a higher boiling point. This would make me think that you system runs too hot for DOT 3 FLUID. In short, don't do it. There is no advantage at all to DOT 3.
Ditto...
 

gathermewool

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New England
Originally Posted By: Sawdusted
Do not put in dot 3 in a brake system designed for dot 4. Not backward compatible.
If you don't know what you're talking about, why post?
 
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Nov 5, 2011
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MTL, CANADA
Originally Posted By: asand1
I believe the fluids themselves are completely compatible, and the materials on the system would ne compatible with DOT 3, but dot 4 has a higher boiling point. This would make me think that you system runs too hot for DOT 3 FLUID. In short, don't do it. There is no advantage at all to DOT 3.
+1
 
Joined
Dec 20, 2009
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Utah
DOT3, 4, 5.1 are all higher steps in boiling wet/dry temps and are comparable, non silicone fluids. I use 5.1 in my trackday bike and that stuff will suck the moisture right out of bare skin like a sponge. Great for hi temps in systems. DOT5 is silicone...only for systems designed for the stuff. DOT4 is all I have ever really needed for street vehicles.
 
Joined
Dec 2, 2002
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Washington St.
Well...the borate esters that are the difference between DOT4 and DOT3 do absorb moisture from the air more readily. If you use DOT4, do flush and renew it regularly. It is not as amenable to negligence as DOT3. The unofficial DOT4+ designation is very similar to DOT5.1---even higher wet boiling point than DOT4.
 
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Nov 30, 2004
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SD
If this is for an older car, I really like (and recommend) DOT 5. I realize it's not recommended for newer vehicles with ABS (its slightly more viscous), and that's fine. I have it in my old Mopars, and it's been great. What I do, is suck most of the DOT 3 out of the M/C, fill it with DOT 5, and bleed 'til I see purple at each wheel. Don't believe all the scare tactics online about DOT 5. More reading: http://www.moparaction.com/Tech/quest/BINDER_JUICE.html
 
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Apr 30, 2014
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MN
The biggest issue I see with Dot5 is that it does not absorb water, if you end up with moisture condensing in the system it will settle to the lowest point and stay there. As long as it's not a spot that can rust through or a caliper it's probably not that big of a deal.
 
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May 26, 2014
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Columbus,Nebraska
I replace brake fluid ever two years using Valvoline DOT3/DOT4. Withe Russell speed bleeders it is easy to do with no help from the war department. The trouble I have is getting rid of the stuff. I have two Mobil I jugs full of brake fluid and nowhere to take it. Town has a hazardous fluid pick up once a year, but the outfit sponsoring the collection won't take brake fluid. Even the mention of it seems to cage their eyeballs. I can't keep storing used brake fluid forever and want to dispose of it properly, but how? Everyone seems terrified of it like it causes the plague. Any suggestions? Throwing it in some country road ditch is not a solution. Where do shops that do a lot of brake work get rid of brake fluid? When I was working, I just poured the stuff on our generating station coal pile.,
 
Joined
Nov 3, 2013
Messages
1,646
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UT
Originally Posted By: HosteenJorje
I replace brake fluid ever two years using Valvoline DOT3/DOT4. Withe Russell speed bleeders it is easy to do with no help from the war department. The trouble I have is getting rid of the stuff. I have two Mobil I jugs full of brake fluid and nowhere to take it. Town has a hazardous fluid pick up once a year, but the outfit sponsoring the collection won't take brake fluid. Even the mention of it seems to cage their eyeballs. I can't keep storing used brake fluid forever and want to dispose of it properly, but how? Everyone seems terrified of it like it causes the plague. Any suggestions? Throwing it in some country road ditch is not a solution. Where do shops that do a lot of brake work get rid of brake fluid? When I was working, I just poured the stuff on our generating station coal pile.,
Next time your city comes around, tell them it is hydraulic fluid.
 
Joined
Jun 27, 2012
Messages
146
Location
MO
Originally Posted By: MolaKule
Originally Posted By: Colin01
Is there any advantages of using dot 3 brake fluid over dot4/super dot 4 or vice versa? eek
No, because each newer fluid has a higher boiling point. Chemistry of Brake Fluids
Borate esters do hydrolyze to boric acid and ether - the same chemical functionality that keeps them boiling at a higher temperature after exposed to water is problematic if you intend to go for long periods without changing it. My rule of thumb is no more than 2 years on DOT 4 or DOT 5.1 without flush/fill - this is due mainly to buildup of boric acid. Up to 3.5 years is acceptable for DOT 3 for a flush/fill in order to replenish corrosion inhibitors and remove moisture. The key thing is that if you drive in hilly terrain or tend to ride your brakes in traffic jams, then the DOT 4 or DOT 5.1 fluids are going to be advantageous. If you drive in very cold climates, the DOT 3 and DOT 5 fluids will tend to flow better than the borated fluids (Silicone has extremely good cold-flow, and DOT 3 is moderately better than DOT 4 and DOT 5.1). Choose your fluid based on anticipated drive cycle and service interval - and definitely keep OEM recommendations in mind.
 

MolaKule

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Jun 5, 2002
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Iowegia - USA
Quote:
If you drive in very cold climates, the DOT 3 and DOT 5 fluids will tend to flow better than the borated fluids (Silicone has extremely good cold-flow, and DOT 3 is moderately better than DOT 4 and DOT 5.1). Choose your fluid based on anticipated drive cycle and service interval - and definitely keep OEM recommendations in mind.
Maybe, but let's not leave the impression you can mix DOT 5.0 and 5.1 fluids; they are not compatible.
 
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