DOT 5 Brake Fluid???
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Lead Driver
Joined: Feb 2000
Posts: 5,374
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From: Palm Bay, Florida
DOT 5 Brake Fluid???
Just wondering if anyone is running it and their opinions?? My 1965 Mustang was recently restored and they put the stuff in and I understand it absolutely will not harm paint, has a very high boiling point, is silicone based (not synthetic) and heres the kicker...it WILL NOT absorb moisture so evedentally it will allow moisture to form and just sit in the system and possibly rust out the metal parts from the inside out.....
I am running DOT 4 synthetic in my '99 F350 Dually and have great brakes, btw.....
I am running DOT 4 synthetic in my '99 F350 Dually and have great brakes, btw.....
Hotshot
Joined: Jan 2002
Posts: 17,988
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From: La La Land
ALL DOT3/4 is technically "synthetic", so the manufacturers touting it aren't saying something "special" about their products.
Silicone brake fluids (DOT-5) have a tendency to entrain air bubbles (or worse, foam) in systems with a separate ABS pump, causing a soft pedal.
The best applications for DOT-5 fluid that I've found are those older cars without ABS.
Just like your Mustang....
Pop
Silicone brake fluids (DOT-5) have a tendency to entrain air bubbles (or worse, foam) in systems with a separate ABS pump, causing a soft pedal.
The best applications for DOT-5 fluid that I've found are those older cars without ABS.
Just like your Mustang....
Pop
Senior User
Joined: Oct 2006
Posts: 259
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DOT 5 fluids do not have a higher boiling point than most performance DOT4 fluids, and unless you seriously neglect your brake system you will not ever see the wet boiling point of a good DOT 4 fluid. A couple of the classes I race in specifically do not allow DOT 5 fluid because it's practically impossible to bleed all the air out, but in a street car you'll never see anywhere near boiling point unless your seriously doing something stupid. I personally use Motul RBF 600, most of my buddies use it or ATE type200/superblue or Castrol SRF.
Anyways, if the system was redone and they used DOT 5, your pretty much stuck with it without a bit of work to properly clean the system out. The two fluilds do not play well together. Your fine with what you have in that application. BTW, there's more chance of corrosion with DOT 5 than DOT 4, because the moisture isn't absorbed.
Anyways, if the system was redone and they used DOT 5, your pretty much stuck with it without a bit of work to properly clean the system out. The two fluilds do not play well together. Your fine with what you have in that application. BTW, there's more chance of corrosion with DOT 5 than DOT 4, because the moisture isn't absorbed.
Postmaster
Joined: Jul 2004
Posts: 3,156
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From: Yuba City, CA.
It's what I learned as a mechanic for DC powered forklifts many moons ago. I have seen master cylinder seals swell and then fail when people that didn't know mix the two. It was on a deadman brake system thank goodness. I did a quick search and came up with this article. I guess there are 2 kinds of DOT5, I was referencing the silicone based version.
http://www.gabma.us/docs/dot5.pdf
I realize that this could be some Joeblow, but it's something I guess we could write an email to DOW or such if we really wanted hard facts. If I'm wrong, than forgive me, I've been mislead.
http://www.gabma.us/docs/dot5.pdf
I realize that this could be some Joeblow, but it's something I guess we could write an email to DOW or such if we really wanted hard facts. If I'm wrong, than forgive me, I've been mislead.
Cargo Master
Joined: May 2002
Posts: 2,530
Likes: 7
From: Montana
Ranger is correct. u do not want to mix the two brake fluids. It has been done by mistake many times in the military, and if caught soon enuf, u can save it from damage. I have seen it happen a few time sin the Military. The HMMWVs take the DOT 5 where as everything else takes DOT 3
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Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
I know you can't successfully mix the two types. They are completely different, incompatible chemistrys.
I was attempting to get some documentation of seals failing as a result of converting to DOT-5.
That's why I quoted, "They will eat seals up" and asked for more info.
Is there some kind of reaction when the two types are brought into contact? That's something I've never heard of.
At least not yet....
Pop
I was attempting to get some documentation of seals failing as a result of converting to DOT-5.
That's why I quoted, "They will eat seals up" and asked for more info.
Is there some kind of reaction when the two types are brought into contact? That's something I've never heard of.
At least not yet....
Pop
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Lead Driver
Joined: Feb 2000
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From: Palm Bay, Florida
Guys, I totally forgot about the fact that you are not to use DOT5 in ABS equipped systems before I asked the question-sorry.
I can't see any real benefit of the 5 in my Mustang since its hard to bleed-my pedal is soft and spongy since the restoration-I don't think they worked with it enough to get all the air out of it.
I think the main reason for its use around antique/classic cars is the non-paint damaging properties.......I'm seriously thinking of flushing the system with alcohol as my Mustang buddies suggest and put in a good quality DOT4.
I can't see any real benefit of the 5 in my Mustang since its hard to bleed-my pedal is soft and spongy since the restoration-I don't think they worked with it enough to get all the air out of it.
I think the main reason for its use around antique/classic cars is the non-paint damaging properties.......I'm seriously thinking of flushing the system with alcohol as my Mustang buddies suggest and put in a good quality DOT4.
Senior User
Joined: Oct 2006
Posts: 259
Likes: 0
Guys, I totally forgot about the fact that you are not to use DOT5 in ABS equipped systems before I asked the question-sorry.
I can't see any real benefit of the 5 in my Mustang since its hard to bleed-my pedal is soft and spongy since the restoration-I don't think they worked with it enough to get all the air out of it.
I think the main reason for its use around antique/classic cars is the non-paint damaging properties.......I'm seriously thinking of flushing the system with alcohol as my Mustang buddies suggest and put in a good quality DOT4.
I can't see any real benefit of the 5 in my Mustang since its hard to bleed-my pedal is soft and spongy since the restoration-I don't think they worked with it enough to get all the air out of it.
I think the main reason for its use around antique/classic cars is the non-paint damaging properties.......I'm seriously thinking of flushing the system with alcohol as my Mustang buddies suggest and put in a good quality DOT4.
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