What is the purpose and who using it on the street? Any reason why I should'nt use it. I'll be flushing my clutch system very soon and was wondering pros/cons. Thanks.
DOT 5 brake fluid?
- Thread starter davidf
- Start date
David,
The manual clearly stats NOT to use DOT 5 brakefluid in your car.
DOT 5 brake fluid is a silicone based fluid. DOT 3 and 4 brakefluid is glycol based. These two types CANNOT be mixed and if you use silicone based fluid in a glycol based system, it becomes very likely that you system will develop corrosion and leaks as well since the seals and such are not ment to be used in combination with silicone based fluids.
As I have been told, mixing even a slight amount of DOT 4 and 5 together will create a nice sludge and probably in a place in your brake system you will have difficulty reaching for cleaning.
In simple words, DON't use it!! Ever!!
The manual clearly stats NOT to use DOT 5 brakefluid in your car.
DOT 5 brake fluid is a silicone based fluid. DOT 3 and 4 brakefluid is glycol based. These two types CANNOT be mixed and if you use silicone based fluid in a glycol based system, it becomes very likely that you system will develop corrosion and leaks as well since the seals and such are not ment to be used in combination with silicone based fluids.
As I have been told, mixing even a slight amount of DOT 4 and 5 together will create a nice sludge and probably in a place in your brake system you will have difficulty reaching for cleaning.
In simple words, DON't use it!! Ever!!
MvM is totally correct.
You can use DOT 5.1, that is glycol based, but I would not bother, DOT3 for street, GOOD DOT4 for track
. Motul600, ATE come to mind. There are many.
Regards,
LarryB
You can use DOT 5.1, that is glycol based, but I would not bother, DOT3 for street, GOOD DOT4 for track
. Motul600, ATE come to mind. There are many.Regards,
LarryB
The higher the DOT number, the higher the minimum boiling point standards it must meet. This is a good thing, particularly for track use.
Like MvM, I do not recommend DOT 5 brake fluid, for all the reasons he mentions. However, there is another type of brake fluid, called DOT 5.1, that is fine. DOT 5.1 is glycol-based so it can be freely mixed with DOT 3 and DOT 4 fluids, but it has the same high boiling point standards that DOT 5 fluid has.
I use Motul RBF 600. It's a DOT 4 fluid but its boiling points exceed DOT 5.1 minimums. You can read more about various fluids and their boiling points in this previous topic.
Like MvM, I do not recommend DOT 5 brake fluid, for all the reasons he mentions. However, there is another type of brake fluid, called DOT 5.1, that is fine. DOT 5.1 is glycol-based so it can be freely mixed with DOT 3 and DOT 4 fluids, but it has the same high boiling point standards that DOT 5 fluid has.
I use Motul RBF 600. It's a DOT 4 fluid but its boiling points exceed DOT 5.1 minimums. You can read more about various fluids and their boiling points in this previous topic.
Thanks guys. My clutch slave and master have been replaced and I'm replacing the hose as well. I just want whats best for the longevity of the seals, I'll flush it with DOT 3.
A bit harsh. I've converted one car to work with Dot5 and use it in my karts. No problems and my calipers did not stick ever again.
Here are the downsides: it does not mix with DOT 3/4 at all. It cannot be used with ABS or ALB systems due to cavitation. Does not mix/or absorb water, and IF water does enter the system it will corrode everything around it in a big bubble (dot 3/4 absorbs a lot of water keeping it away from the metal parts).
Upsides: It keeps seals fresh even if the system is not used for long periods of time. And because it does not absorb water (at all) it keeps the seals fresh and lubricated. Fluid never goes bad on the shelf and for all these reasons DOT 5 is mil spec.
I'm considering using it my NSX clutch master/slave as is a conventional system that seems to fail because the seals let go. DOT 5 should alleviate this issue. Replace the master/slave and clear the lines with denatured alcohol.
I'm considering using it my NSX clutch master/slave as is a conventional system that seems to fail because the seals let go. DOT 5 should alleviate this issue. Replace the master/slave and clear the lines with denatured alcohol.
^^^^^ That was my reasoning in the begining. With all the clutch slave/master problems, I hoped to prolong my not so old parts.
^^^^^ That was my reasoning in the begining. With all the clutch slave/master problems, I hoped to prolong my not so old parts.
Larry, I was quoting what Drew said. With all the posts about clutch master/slave failures, I was just hoping to prolong the lives of my fairly new item installed. Since I'm changing my hose this weekend I figured it would be a good time to do a flush. I was'nt sure what the silicone based DOT 5 was good for. Guess I'll stick with DOT 3.
So is this opinion or fact? Has it been concluded that seal life is extented? Is there any documentation available to substantiate this?
Thanks,
LarryB
The DOT 5 is used by the US Military (and others, mostly NATO) for a need of non-glycol based brake fluid. One that would not degrade over time, absorb water or impurities and preserve the seals.
It is nice stuff and is a lifetime fluid. It has serious drawbacks for consumer automotive application: as it does not work with ABS and can be really difficult to pour without introducing air bubbles. Installation has to be done correctly or you will cause all kinds of issues that are not present with DOT3/4/5.1
No US automaker specifies DOT 5. I personally use it in racing and in one of my cars where the calipers pistons would stick. Using it in a clutch system is a reasonable use of it.
Here is a reasonable 3rd party info:
http://www.motorcycleproject.com/motorcycle/text/cows-brakefluid.html
http://www.gabma.us/docs/dot5.pdf
Here is smidgen of Mil Spec info (look at the required specs for MIL-PRF-46176!)
http://www.clearcoproducts.com/pdf/specialty/PRF46176.pdf
And in typical Army format (just like my M-16 manual)
http://www.clearcoproducts.com/pdf/specialty/Use-Only-Sil-Brake-Fluid.pdf
You would think the US MIL and NATO stuff would be free available on line (I suspect it is, but it is not being indexed and you have to know where to go look for it [and I don't]). Maybe not it is not surprising, the military might be afraid of any information leaking out so they just deny it all.
It is nice stuff and is a lifetime fluid. It has serious drawbacks for consumer automotive application: as it does not work with ABS and can be really difficult to pour without introducing air bubbles. Installation has to be done correctly or you will cause all kinds of issues that are not present with DOT3/4/5.1
No US automaker specifies DOT 5. I personally use it in racing and in one of my cars where the calipers pistons would stick. Using it in a clutch system is a reasonable use of it.
Here is a reasonable 3rd party info:
http://www.motorcycleproject.com/motorcycle/text/cows-brakefluid.html
http://www.gabma.us/docs/dot5.pdf
Here is smidgen of Mil Spec info (look at the required specs for MIL-PRF-46176!)
http://www.clearcoproducts.com/pdf/specialty/PRF46176.pdf
And in typical Army format (just like my M-16 manual)
http://www.clearcoproducts.com/pdf/specialty/Use-Only-Sil-Brake-Fluid.pdf
You would think the US MIL and NATO stuff would be free available on line (I suspect it is, but it is not being indexed and you have to know where to go look for it [and I don't]). Maybe not it is not surprising, the military might be afraid of any information leaking out so they just deny it all.
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In an NSX, I'd stick with DOT 4 as a minimum.
guys stay with the dot 3, i have used dot 5 since late 70's ,it is not hygroscopic (does not absorb moisture) also it is more compressible than ordinary brake fluid (results in a spongy pedal) ,most manu. will not use it in an abs system because it tends to develop air bubbles when cycled rapidly, yes it has some good qualities (dont want to get into a pissing match about brake fluid) but dot 3 will be fine for us
...or DOT 4 or DOT 5.1, none of which have the problems associated with DOT 5 fluid. DOT 4 and DOT 5.1 have higher boiling points than DOT 3, which means better protection against fluid boiling and brakes fading.
I will only use Dot 4 in my car. And don't forget to change it at least every two years.:smile:
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The discussion was about using DOT 5 in the clutch system to potentially make the life of the clutch master/slave near indefinite.
It would be a reasonable to think that, based on the properties of DOT 5, one would never have to replace the clutch cylinders again.
NOBODY is arguing using DOT 5 for the brake system (at least not with a ABS/ALB system present).
It would be a reasonable to think that, based on the properties of DOT 5, one would never have to replace the clutch cylinders again.
NOBODY is arguing using DOT 5 for the brake system (at least not with a ABS/ALB system present).
That is absolutely correct. Since there are many post about clutch master/slave failures, I got to thinking, Hmm, what if!
