dcmodels

My primary purpose in posting this, is to give a general idea of how Honda Dot3 brake fluid compares with other brake fluids. This is hardly a full survey of many brands, just an attempt to determine if Honda fluid is really at the bottom of the quality scale or somewhere in-between.

Also, there is no information available concerning brake fluid additives, which would allow a quality comparison. The information here only allows a comparison by boiling points. And some viscosity information is provided, but that data is particularly difficult to find.

Other than empirically, I know of no way to compare the hydroscopic property of brake fluids (how quickly they absorb moisture).

HAS ANYONE EXPERIENCED ANY PROBLEM USING A BRAKE FLUID OTHER THAN HONDA?
There are many threads on AcuraZine (AZ) concerning the use of various different brake fluids, in various Acura models (other than RDX). You should do a search and read some of them, if interested.

I have not seen any posts stating problems with using other than Honda Dot3, but I would be interested if someone has had such a problem, please post to this thread. Thanks.

BRAKE FLUID TYPES:
Dot 2 brake fluid is obsolete, and if you have some hiding in the garage, please recycle it.

Dot 3, 4, and 5.1 are compatible, although to mix them will reduce the overall performance. Dot 5 fluid is silicone based, and should never be used in a street driven car. Moisture will not ‘dissolve’ in Dot 5 fluid, but will pool in the bottom of your brake calipers and rust the pistons.

Dot 3, 4 and 5.1 absorb moisture, and disperse it through out the total fluid, helping to prevent rust. And that is why brake fluid should be replaced each year. I don’t care what your vehicle type, or what the Owner’s Manual says. Once per year if you plan to keep your car any length of time, or else you will be replacing the VHS system or the ABS controller, because of rust, corrosion, and crap in the tiny orifices of the ABS controller.

Its not like the old days, when I started driving – after a few years, you would just replace the rusted out wheel (non-disk-brake) cylinders, and fill up with new fluid. These days, ignoring maintenance of brake fluid (replacing it) will lead to very costly repairs.

Do not use racing brake fluid in your street vehicle, unless you are tracking it and replace the fluid after every race day. Racing fluid is skewed toward the highest boiling point, but has few corrosion inhibitors. After race day, put street fluid back into the system, until the next race day. Racers use FORD Dot3 because it is cheap, and has a very high dry boiling point. But the wet boiling point is unremarkable. That is OK since the fluid is only going to be used for a few hours.

NOTE: a plastic brake fluid container bottle allows (slow) moisture absorption, right through the bottle, into the brake fluid inside. For information about how to read the date code on fluid containers, use this link:

LINK to How to Read DATE CODES:
https://acurazine.com/forums/showthread.php?t=775691 post #2

Data/ items in this post with dates were taken from the official manufacturer MSDS. Other data was taken from general web postings, so may not be correct.

WHAT ABOUT VISCOSITY?
Brake fluid, like other fluids for your car, should not be too thin at a high temperature, otherwise it will either boil or not function properly. Likewise, it should not be too thick at low temperature, else it will not flow and the brakes (esp the ABS system) will not function properly.

Some European vehicles specify low viscosity brake fluids, such as the ATF SL.6, for improved ABS performance. I have no idea what people use here in the USA, since such fluids are difficult to obtain – perhaps from the dealer?


Viscosity Comparison cSt @ 100 C/ 20C/ -40C
(BRAKE Fluids - calculated values in bold RED)
2.26/ 17-18/ 1,400 = ATE Super Blue Racing 01/25/11
2.10/ 15-17/ 1,100 = Castrol GT LMA Dot-4 05/02/11
2.3/. 16.76/ 1,200 = Castrol Response Dot-4 (Europe only) 08/08/01
2.03/ 14.5/ 900-1100 = Pentosin Super Dot-4 (OEM GM p/n 8895-8860) 05/14/01
1.90/ 12.3/ ...700 = ATE SL.6 Dot-4 ISO class-6 (Europe only) 09/07/12
...x/ ...5/ .....x = AC Delco Dot-4 (Ethoxinol 430) (AU only) June 2010


THE FOLLOWING ARE THE DOT (department of transportation) REQUIREMENTS FOR BRAKE FLUID:
REQUIREMENTS: ....DOT-2 DOT-3 DOT-4 DOT-5 DOT-5.1 (minimums)
Dry Boiling point ..374 ..401 ..446 ..500 ....500 (Fahrenheit)
Wet boiling point ....x ..284 ..311 ..356 ....356 (Fahrenheit)
cSt @ -40C (max) .....x 1,500 1,800 ..900 ....900
cSt @ 100C (min) .....x ..1.5 ..1.5 ..1.5 ....1.5

NOTE: Honda Dot3 wet boiling point is not specified in the MSDS, but must be at least the minimum for Dot3 type fluid, which is 284 degrees.
....................... DRY ..WET (boiling points in Fahrenheit)
Honda Dot 4 ............. ? ....? (p/n 08203-0004) / from motorcycle shops
Honda Ultra Dot 4 ....... ? ....? (p/n ?????) / United Kingdom
Valvoline Dot 3/4 ..... 446 ..311 (yellow color) 03/08/12
Honda Dot3 ........... >450 ....? (p/n 08798-9008(A)) 01/26/10
BG Dot3 ............... 480 ....? (yellow to amber) 12/15/10
BG Dot4 ............... 480 ....? (amber) 09/01/10
Delco Supreme 11 Dot3 . 490 ....? (GM p/n 1237-7967, pale yellow) 06/08/95
Prestone Synthetic Dot4 500 ..311
Castrol LMA DOT 3/4 ... 509 ..311 (yellow/ amber color) 05/02/11
Bosch Dot4 ............ 509 ..329
Pentosin Super DOT4 ... 518 ..338 (OEM GM Dot-4 p/n 8895-8860) 01/11/11
Castrol Response DOT4 . 518 ..338 (Europe only) 08/08/01
ATE Super Blue Racing . 536 ..388 (metal can: blue color) 01/28/11
ATE TYP 200 ........... 536 ..388 (metal can: amber color)
Ford Heavy Duty DOT3 .. 550 ..290 (absorbs moisture quickly)
Performance Friction .. 550 ..284 (metal can)
Motul Racing 600 Dot4 . 585 ..421
Castrol SRF Dot4 ...... 590 ..518 ($75/ liter)
__________________________________________________ _______________
NOTE on VISCOSITY CALCULATIONS: the following web site can be used to calculate a viscosity CURVE for an oil, if either the viscosity at a known temperature is provided, or if the VI (viscosity index) is provided. Also, viscosity conversions can be done from one system to another. Different conversion tables on the site use different numbers of decimal points, which can affect the accuracy of the conversions. I do not know how accurate this conversion program really is - no data is given on the site.
LINK: http://widman.biz/English/Calculators/Graph.html

SOURCES OF MSDS information:
Most major oil web sites will offer online MSDS (manufacturer safety data sheet) information. However, Honda does not manufacturer its own fluids. And uses fluids from various different manufacturers. Sometimes a distributor will offer Honda MSDS information. Otherwise, the following two links can provide additional MSDS information, if unavailable elsewhere.

LINK:http://www.worldpac.com/msds/
LINK: http://www.msdsonline.com/FindMSDS/Default.aspx

737 Jock

Good post. Many people do not understand how important it is to replace brake fluid.

For many years I have used Valvoline Synpower DOT 4 brake fluid in my VWs and Mitsubishis. Synpower costs less than OEM brake fluid and is readily available everywhere (they just call it "Synthetic" now).

Soooo...I tried it in the RDX. (As you know, the manual says Honda Heavy Duty DOT 3 only.)

Oops! The pedal had a strange feel. Not springy like trapped air, but it would slowly continue to push down as if fluid was escaping past the seals in the master cylinder. Mind you, the car was drivable, but the strange pedal travel bothered me a lot more than the $ I saved. I was worried about replacing the master cylinder, because I tried to save a few bucks on fluid.

I flushed out the Synpower with Honda Heavy Duty DOT and the pedal feel and travel returned to normal. That was a few years ago and its been Honda brake fluid ever since.

Same thing with power steering and coolant: Honda only.

Vividsi

I noticed the manual says Honda Dot 3 only but im using MOTUL DOT 4 and it seems fine.

dcmodels

Quote:

Originally Posted by 737 Jock

... For many years I have used Valvoline Synpower DOT 4 brake fluid in my VWs and Mitsubishis. Synpower costs less than OEM brake fluid and is readily available everywhere [DCmodels edit: sorry, but no] (they just call it "Synthetic" now). ... I was worried about replacing the master cylinder, because I tried to save a few bucks on fluid. ... I flushed out the Synpower with Honda Heavy Duty DOT ... That was a few years ago and its been Honda brake fluid ever since. ...

The current version of Valvoline Dot 3/4 is easily available. But it is *not* the same as the old Valvoline Synpower from several years ago. About 2007 Valvoline changed the NAME, SPECIFICATIONS, and CHEMICAL composition of their brake fluid. This is clearly stated on the Valvoline web site FAQs page, although I may have the exact date of the change wrong. The current version has much lower DRY and WET boiling points, compared with the old Synpower version.

The old Synpower version was a favorite among Corvette drivers, and people who tracked their cars. The Synpower name is still used for Valvoline brake fluid available in Europe. I do not know if the European version actually differs from the USA version. But, as can be seen from the specs in my original post above, the current Valvoline brake fluid is unremarkable, and nothing special. It only just meets the minimum specs for Dot-4.

Quote:

Originally Posted by Vividsi

I noticed the manual says Honda Dot 3 only but im using MOTUL DOT 4 and it seems fine.

Thanks. There are multiple versions of Motul Brake Fluid. Either a specific Motul part-name or part-number would be helpful for others, who wish to use the exact same fluid as you have used.

Vividsi

I used Motul RBF600 synthetic DOT 4

737 Jock

Thanks for pointing out the difference between Synpower and the new Valvoline synthetic. I'll check those specs and be looking into a better fluid for the Dubs and Mitsus.

dcmodels

MEASURING BRAKE FLUID MOISTURE CONTENT

MOISTURE IN BRAKE FLUID CAUSES CORROSION and ABS BRAKE PARTS ARE REALLY EXPENSIVE

The purpose of this post is to indicate a general idea of how much moisture brake fluid will absorb, and how quickly. I have purchased an electronic device to measure the moisture content of brake fluid. This post discusses only the testing-device which I purchased, without any comparison against any other device.

And I wanted to determine just how efficient is the brake fluid flush performed by my Acura (and Chevy) dealers. That is, does the dealer technician remove all of the old moisture laden fluid, and how long does it take for the ‘new’ fluid to absorb more moisture?

MY CONCLUSIONS:
I have reached the following conclusions, based upon the test measurements that I took. You are free to reach your own conclusions:

Ø Brake fluid, especially Dot3 type, absorbs enough moisture in the vehicle brake system, in only 1-year, that it should be replaced yearly – in my opinion.

Ø Brake fluid absorbs enough moisture, even when stored in a factory sealed bottle, that it has a definite shelf life. I am uncertain just how long that is, due to limited data points.

Ø Brake fluid stored in a tightly-capped but unsealed/ opened bottle, absorbs moisture at (almost) the same rate as it does in the ‘sealed’ vehicle brake system. I have had some success sealing bottles ‘air-tight’ by stretching a square piece of food clear-wrap over the opening, then tightening the bottle cap over that – never tried it with brake fluid, however.

Ø I am not convinced that the Chevy dealer is doing a ‘good’ brake fluid flush, or else the brake fluid they are using is crap – see test results below. Another possibility is that the machine used to perform the brake flush is not protecting the fluid from moisture absorption. Remember, the dealer does not open a new can of brake fluid to perform your flush. They fill a flush machine with fluid, and whatever is left is used on the next flush (next month, next year?)

Ø I do not have enough data to ‘grade’ the brake fluid flush performed by my Acura dealer. Again, check my test results below, and decide for yourself.

The following picture shows the typical effect of moisture on the boiling point of Dot3 brake fluid. Understand, this picture was ‘stolen’ from the web, and I have seen it posted many times on various sites. But that does not indicate how valid it is, especially the comparison of moisture content versus time (years). Just consider it as a general guideline with respect to Dot3.

And remember that type Dot4 brake fluid will graph completely differently. Dot4 absorbs moisture at a different rate compared with Dot3.

PICTURE: Dot3 moisture absorption versus time


DEVICE for MEASURING MOISTURE in BRAKE FLUID:
There are many different electronic devices for measuring the moisture content of brake fluid. The price range is about $20 up to several hundred dollars.

The particular device that I used, as discussed here, is the one shown in the following link. I purchased this particular device, because it is simple to use, requires no calibration, is inexpensive, and carries a lifetime warranty.

LINK: brand PERFORMANCE TOOL, purchased from Oreilly-Auto, p/n W181, UPC: 39564045981, price $32.99, LIMITED LIFETIME WARRANTY, device manufactured in Taiwan, battery manuf. in China.
http://www.oreillyauto.com/site/c/detail/PFM0/W181/N0675.oap?ck=Search_N0675_-1_-1&pt=N0675&ppt=C0067

PICTURE: measuring device []


In searching online for this device, I found 20 or so different items, all of which, based on the poor online pictures, are exactly the same as the device that I purchased. The prices ranged from $20 to almost $100. Most carried no warranty at all. For example, AutoZone carries what appears to be this same device, for $30 but without any warranty. Also, Oreilly Auto sells the following item, advertised with the same picture as the item in the link above.

LINK: brand OTC, available from Oreilly-Auto, p/n 4598, UPC: 731413559860, price $43.99, 1-YEAR LIMITED WARRANTY.
http://www.oreillyauto.com/site/c/detail/OTC0/4598/N0678.oap?ck=Search_N0678_-1_-1&pt=N0678&ppt=C0067

Also, note that although every device I viewed appears to be exactly the same, the Brand and country of origin, are not always the same. So the various devices may actually be different. Perhaps they are all built to the same design, under a license agreement?

Also, I found at least two other different, but very similar measuring devices. That is, the other devices are about the same size, function in a similar manner, but have a different number of LED indicators, slightly different physical configuration, and different writing printed on the testing-device body.

HOW DOES THE MEASURING/ TESTING DEVICE FUNCTION?
The device measures the electrical resistance between the two metal pins, when the pins are submerged into brake fluid. The resistance varies, depending upon the percentage of moisture present in the brake fluid. Water is a good electrical conductor, brake fluid ‘not-so-much’.

Is there a difference between Dot 3 and Dot 4 (or Dot 5.1) fluids? Well, there is definitely a subtle chemical difference, although all of these three brake fluid types are glycol based. Dot-5 brake fluid is silicone based, and another ‘animal’ altogether. I have been unable to determine if or how this might affect the moisture readings taken by the measuring device. The device instructions make no mention of there being any problem in this regard.

However, the more complex and expensive brake fluid moisture measuring devices, do state that the individual device must be calibrated for the type of brake fluid being measured.

HOW TO READ THE MEASURING DEVICE:
This measuring device can give you a good indication of how fast the brake fluid in your own vehicle is absorbing moisture. But the device cannot give you an absolute measurement of the moisture level in your brake fluid.

The brake fluid tester has 5 LEDs. The number of LEDs illuminated, indicates the amount of moisture in the brake fluid, as follows:

1 = zero moisture (and good battery)
2 = less than or equal to 1%
3 = less than or equal to 2%
4 = less than or equal to 3%
5 = equal to or greater than 4%

The question is just how accurate is the measuring device, and I have not tried to calibrate it. So, there is no way of knowing if 2 LEDs illuminated, means 0.1% moisture, or 0.9% moisture. We only know that there is more than 0.0% and less than or equal to 1.0% moisture, within the actual accuracy of the device itself, which accuracy cannot be determined without calibration of the device.

This is important, because if you measure some brake fluid just after opening its container, and the reading is 2 LEDs, then there may be only a trace amount of moisture, or there may be as much as (almost) 1% moisture in the fluid.

But if the fluid has been in your vehicle brake system for 1-year, and the measurement is still only 2-LEDs, then you will know that very little moisture has been absorbed during the year of service, that is, less than 1% of moisture has been absorbed.

HOW TO TAKE A MEASUREMENT with the MEASURING DEVICE:
The device instructions state to “… immerse the pins in brake fluid up to the rim of the plastic body …”. My partner says that means to insert the pins until the plastic body of the device almost, but does not quite, touch the surface of the brake fluid. I think it means to insert the pins until the plastic body of the device just touches the surface of the brake fluid.

Actually, I think it should not matter which of the above is correct. For every reading below, except one, it did not matter whether the pins were fully immersed into the brake fluid, or not. The readings were consistently the same.

For my readings taken from the 1998 S-10 Chevy Blazer master cylinder, if the pins were barely inserted into the brake fluid, the reading was <2%. If the pins were inserted most of the way into the brake fluid, the reading was <3%. If the pins were inserted into the brake fluid until the tip (rim) of the plastic device body just touched the surface of the brake fluid, the reading was consistently >4%.

So why was there a procedural difference, between the readings taken from the Chevy, and the other readings below? Well, the Chevy Blazer brake fluid looked somewhat dark, compared to the brake fluid in all of the other readings. Perhaps the ‘gunk’ in the Chevy brake fluid, resulting from heat and oxidation, had some effect on the procedure used for taking the readings.

Anyway, for consistency, I have decided that the proper testing method is to immerse/ insert the two pins on the measuring device, until the plastic part (tip) of the device just touches the surface of the brake fluid. It is not possible to estimate the same amount of device pin immersion for each test, unless the device is immersed until the rim of the plastic body touches the surface of the brake fluid.

SAMPLE MEASUREMENTS from STORED BOTTLES OF BRAKE FLUID:
The following measurements were taken in the order listed, using the device being discussed. The measurements were taken in the kitchen sink (do not inform the female owner of this kitchen). Brake fluid was poured into a small diameter, tall, clean and dry glass jar for measurement, limiting the amount of brake fluid to be contaminated during measurement. Approximately 2-3 ounces was required for measurement.

The measurements were made with an ambient temperature of 70 degrees, and the relative humidity was approximately 50-60%. The three bottles used in the following tests, were stored in a heated basement: 60 degrees and relative humidity of 30-50%, lower humidity in the summers and higher in the winters.

1) HONDA Dot 3 p/n 08798-9008
Manufactured 01 Apr 2010
Purchased, Opened and Stored 10 Oct 2010
Tested in bottle 18 Nov 2012: <3%
NOTE: a second measurement was taken after measuring the CASTROL brake fluid (next), and the HONDA reading of <3% was repeated. The Honda fluid bottle was only about 1/3-full during storage.

2) CASTROL GT LMA Dot 4 p/n 502 LBL 502J, stock# 00320-44
Manufactured 09/176 = 176th day of 2009
Purchased, Opened and Stored Nov 2009 approximately
Tested in bottle 18 Nov 2012: <1%
NOTE: Dot 4 fluid absorbs moisture slower than Dot 3 fluid, so this measurement is not unexpected. I would have been surprised by a higher reading. The Castrol fluid bottle was approximately 2/3-full during storage.

3) VALVOLINE synthetic Dot 3/4 p/n 601457
Manufactured UNKNOWN
Purchased and Stored June 2010 approximately
Opened 18 Nov 2012
Tested in bottle 18 Nov 2012: <1%
NOTE: as indicated above, by using the measuring device discussed here, there is no way of knowing whether the bottle has absorbed only a tiny insignificant amount of moisture, or if there is almost 1% of moisture in the bottle. Do note that there is a general caution that brake fluid has a self life of 2-3 years. So it is unfortunate that Valvoline does not print a manufacturing date on its brake fluid. As already noted, the Valvoline fluid bottle was only opened for the first time, in order to take this measurement.

SAMPLE MEASUREMENTS from TWO VEHICLES:
The following measurements were taken in the order listed. For the vehicle measurements, the ambient temperature was 48 degrees and the relative humidity was about 50%. The engines of the vehicles were warm, but not hot. That is, the vehicles had been driven, but allowed to sit with the hood open for about 1 hour.

The next measurement was taken from the Master Cylinder of a 1998 Chevy S-10 Blazer. The brake fluid has been flushed, by the Chevy dealer, at approximately 1-year intervals for the past 10 years, using BG Dot3 fluid. The first flush occurred after the vehicle was 4-5 years old, and the brake fluid was truly nasty. The latest flush was performed 17 August 2011.

1) Chevy 1998 S-10: BG Dot3
Flush 17 Aug 2011
Tested in vehicle Master Cylinder 07 Dec 2012: >4%%

The next measurement was taken as a control and verification, since the reading on the Chevy was higher than unexpected, only 15 months after a dealer flush. Measurement was taken inside, at a temperature of 72 degrees, and a relative humidity of about 50%.

2) VALVOLINE synthetic Dot 3/4 p/n 601457
Manufactured UNKNOWN
Purchased and Stored June 2010 approximately
Opened 18 Nov 2012
Tested in bottle 07 Dec 2012: <1%

The next measurement was taken from the Master Brake Cylinder of a 2009 RDX. The brake fluid has been flushed 3-times, by the Acura dealer, at approximately 1-year intervals, using Honda Dot3 fluid. The latest flush was performed 23 August 2012. The RDX was manufactured Dec 2008 and purchased 15 Mar 2009.

3) RDX 2009 – Honda Dot3
Flush 23 Aug 2012
Tested in vehicle Master Cylinder 07 Dec 2012: <1%

dcmodels

PROBLEMS and CAUTIONS WHEN USING CONDUCTIVITY TYPE BRAKE FLUID TESTERS, TO MEASURE THE MOISTURE LEVEL

I conclude that without proper calibration, no device should be used, which relies upon electrical conductivity to determine the moisture level in brake fluid.

LINK: explains why conductivity varies between types of fluid and depends upon which additives are used. The following is a short quote from the link.
http://www.brake-eng.com/Braking-News/The-Dangers-of-Conductivity-Type-Brake-Fluid-Testers/

Unfortunately, this measurement principle [ed: determine moisture level by electrical conductivity] is fatally flawed as the conductivity of new brake fluids varies substantially, from not only between DOT 3, DOT 4 or DOT 5.1 types but also from formulation to formulations within a DOT grade depending on the additives used. This means that unless a conductivity tester is calibrated on one manufacturer’s product and then used for that product only, it is likely to give very inaccurate results.

LINK: Wilmar Corp. sells the brake fluid moisture measuring device discussed in this and the previous post
http://performancetool.com/contact.aspx

LINK: brand PERFORMANCE TOOL, a brand-subsidiary of Wilmar Corp., purchased from Oreilly-Auto, p/n W181, UPC: 39564045981, price $32.99, LIMITED LIFETIME WARRANTY, device manufactured in Taiwan, battery manuf. in China.
http://www.oreillyauto.com/site/c/detail/PFM0/W181/N0675.oap?ck=Search_N0675_-1_-1&pt=N0675&ppt=C0067

There is nothing, either on the Wilmar Corp web site, or on the measuring device packaging, that would indicate that the device operation would depend upon the brand or type of brake fluid. However …

During my tests, the BG brand of Dot3 brake fluid measured at >4% moisture. That was for both a new unopened bottle, as well as fluid that had been in my Chevy vehicle for 15 months. Yet an unopened bottle of Valvoline brand brake fluid measured <1% moisture.

Clearly, the brand and composition of the brake fluid does influence the reading obtained by the Performance Tool moisture measuring device.

==========================
Based upon the measurements I have taken from Honda Dot3 brake fluid, as reported in my previous post, it may be possible to calibrate the Performance Tool measuring device for Honda fluid. Since that is my primary interest, if I should determine that it is possible to calibrate this device for Honda brake fluid, I will report any such information at a later time.

==========================
But for now, I conclude that without proper calibration, do not use either this device or any similar device, to determine the moisture level in brake fluid.

simplicity

Has anyone used ATE Type200 fluid or any of the pentosin fluids? I have called all around and all the acura/honda dealers just stock the "normal" dot 3 fluid and not the heavy duty one as called for by the owner's manual.

Also should the RDX brake fluid be replaced with a low viscosity fluid or any normal dot3/4 fluid is fine?

I plan to flush with a liter of ATE type 200 or Pentosin super dot 4