BRAKE FLUID - USE DOT 4 ONLY

Brake fluid is the hydraulic medium employed to transmit actuation forces within the braking system. Compliance with stringent requirements is essential to ensure reliable brake system operation. This requirements are defined in various standards of similar content (SAE J 1703, FMVSS 116, ISO 4925). The performance data contained in FMVSS 116 (Federal Motor Vehicle Safety Standard), mandatory in the United States, serves as an international reference.

The equilibrium boiling point provides an index of the brake fluid's resistance to thermal stress. The heat encountered in the wheel cylinders (with the highest braking temperatures in the entire braking system) is especially critical. Vapor bubbles can form at the temperatures above the brake fluids instantaneous boiling point, resulting in catastrophic brake failure.

The wet boiling point is the fluids equilibrium boiling point subsequent to moisture adsorption under specified conditions (approximately 3.5%). Hydroscopic (glycol based) fluids respond with an especially pronounced drop in boiling point when contaminated with water.

DOT SPECIFICATIONS

DOT 3 is polyethelene glycol and is amber colored
DOT 4 is polyethelene glycol with esters and is amber colored
DOT 5 is silicone and purple colored to prevent its accidental use
DOT 5.1 is polyethelene glycol with esters and is amber colored

DOT 3 - dry boiling point = 205C = 450F
wet boiling point 140C = 284F

DOT 4 - dry boiling point 230C 513F
wet boiling point 155C = 333F

DOT 5 - dry boiling point 260C
wet boiling point 180C

DOT 5.1 - don't have exact specifications but it is used in extremely high performance motorcycle braking systems like the Brembo system on the KTM 640 Adventure Rally race bike! Also used in Formula 1 exotic race cars as well.

ALL VOLKSWAGEN TDI'S SHOULD USE DOT 4 BRAKE FLUID ONLY

Most brake fluids are glycol ether compounds. These generally consist of monoethers of low polyethelene glycols and are therefore polyalkylene glycol ether compounds. Although these compounds may be used to produce a brake fluid which conforms to DOT 3 requirements, their undesirable hygroscopic properties cause these fluids to absorb moisture at a relatively rapid rate with an attendant swift reduction in the boiling point.
If the free OH (hydroxyl) groups are partially esterified with boric acid, the result is superior DOT 4 brake fluid capable of reacting with water and neutralizing its effects. Also, the DOT 4 brake fluid's boiling point drops much more slowly than that of DOT 3 when contaminated with water, increasing the service life of DOT 4 greater than DOT 3. DOT 4 is superior to DOT 3 in every possible manner and is much preferred for brake fluid in modern automobiles.

There are two other brake fluids that are used for racing and are not approved for road use, they are mineral-oil fluids and silicone fluids. DOT 5 is silicone brake fluid. These great advantage of these fluids are that they are not hygroscopic, so the boiling point does not drop owing to moisture adsorption. The disadvantage of these products is that they have higher compressibility and inferior lubrication, which reduces their general use. Also, they should NEVER be mixed with brake fluids containing glycol ethers (or vice versa) as this destroys the elastomers in the fluids altering the relationship between temperature and viscosity detrimentally.

Remember, DO NOT SPILL Brake Fluid on your paint, it WILL dissolve your cars paint! Also, do not spill it on radiator hoses either.

Take home message is to use only DOT 4 in your VW TDI no matter what year or type it is. Only use from an unopened container and avoid all contact with water. Also avoid all contact with any dirt or debris that would contaminate the brake lines. Do not spill any brake fluid on your paint, if you do, wipe it up immediately and wash with soap and water or else you paint will simply dissolve.

DOT 4 should be good for up to two (2) years of use depending on the individual cirmumstances before a change is mandated.

REMEMBER, just because some slacker says that he uses the CHEAPEST Brake Fluid he can possibly pick up for free or suck out of a junker at the auto wrecker yard, DO NOT PAY ANY ATTENTION to his false information. He may say he has drive 400,000 miles on the same brake fluid and never changed it, or that he adds 20cc of water to his brake fluid to help cool it off whenever it gets hot. Or that he lives in Florida and there are no big hills around so his brakes never get that hot. Whatever BS he says, YOU KNOW and I KNOW his BS is dangerous information and loaded with crap. Do not trust yourself or your family in your VW TDI to his senseless information void!

I happen to like Castrol LMA brake fluid - this is one product I can recommend without reservation ...VW and Audi dealers have used it for years ....

TooSlick

I was told that DOT-3 or DOT-4 were fine for our VWs. But of course I got this advise from an unreputable source - a VW dealer.

Here is a nice link to the VW Corrado Racing club regarding brake fluids:
www.corrado-club.com/corrado/faq/brkfluid.html

BTW, only two chemical companies produce the entire ethylene glycol stock for the entire North American continents brake fluids, Union Carbide and Ethyl Petroleum.

Like I just previously said directly and quite explictly above here HowardZ, it is a waste to use DOT3, it attracts and absorbs more moisture and has a shorter half-life, there is NO VALID reason to use DOT 3 instead of the vastly superior DOT 4, unless the old tractor abandoned in the field on the side of the highway your are sucking the brake fluid out of for an emergency just happens to be DOT 3!

Well Skypup
I have 2 or 3 unopened 1 quart cans of Dot3.
Your referenced web site blasts teh DOT-5, but does not condem the DOT-3. Obviously DOT-4 is superior, but DOT-3 isn't so bad. It's like our using up old stock of CG4 oil even though CH-4 is superior?

Hate to clue you in here HowardZ but DOT 3 is pretty pathetic and does not nearly meet the OEM DOT 4 brake fluid that comes standard issue in your VW from the factory. IMHO, it is plain stupid to use DOT 3 for any reason you can think of. Of course, it is your ride!

As an analogy, if your water pressure dies and you are thirsty with no water available at the water faucet, just because the toilet contains a couple of gallons doesn't mean it is good water to drink, then again, maybe it does depending on what you know about clean water and the human digestive tract.

Take your DOT 3 to a toxic waste roundup and dispose of it, use DOT 4 only.

BTW, you may wish to change your handle from "SkyRuppy" to "Ric's Genetic Clone" if you continue on that line of logic.


[This message has been edited by SkyPup (edited February 14, 2000).]

What makes you so sure that VW recommends DOT-4 or that VWs come from the factory with DOT-4?
It doesn't say DOT-4 in my owner's manual.

Howard, maybe you can give or sell that DOT 3 fluid to someone with an older car who can use it..

Skypup, Isn't is obvious? if anyone should have the screen name "Skypuppy" it's TURBO STEVE... LOL! Has he asked you for your autograph yet?

DOT 3 should be considered as the lowest possible acceptable standard. It'll make your car stop, but that's about it. DOT 4 is a substantial improvement in all the critical area, including boiling point and resistance to water-induced corrosion. It's also better for your seals.

DOT 5, while measurably superior to DOT 4, is not compatible with VW's brake system.

In previous discussions on this subject, someone mentioned that high-performance DOT 5.1 fluid is OK for VW systems. I don't know that for a fact, though. Anybody have any specific information about why that might be the case?

-mickey

NOTE: VW will change your brake fluid for free as long as you are under the 24 month period regardless of mileage.

I use DOT 5.1 in my motorcycles and get the special expensive 5.1 Bel-Ray motorcycle racing brake fluid, it is NOT mineral oil or silicone oil and is compatible with DOT 4 in an emergency, however basically it should not be mixed in with anything else that has not been previously flushed out.

DOT 5 is silicone and although it is DOT approved, it is NOT something some here would be using except under very specialized circumstances on a professional race track.


HOWARD -> VOLKSWAGEN TDI'S COME WITH DOT 4 BRAKE FLUID STANDARD STOCK OEM FROM THE FACTORY -> YOU CAN QUOTE ME ON THAT or post that same question all over the Vortex, NewBug.org, etc. and see if anyone can possibly give you a better answer than that. They can't and they won't since there is NO other answer except the absolute fact that VW TDI's have DOT 4.

Now, repeat after me:

DOT 4, DOT 4, DOT 4, DOT 4, DOT 4, DOT 4, DOT 4, DOT 4, DOT 4, DOT 4, DOT 4, DOT 4, DOT 4.

Get it NOW?????

Skypup, I am not trying to fight with you. I am just wondering where you read "DOT 4" with regards to our VWs. You have many more manuals than I have. I am just asking how you are so sure; where you read it.

Ok, I just went to the parking lot and looked under my hood. I loosened the difficult to get to brake fluid reservoir cap and it reads "Use original brake fluid". But on the reservoir body it says "DOT-4" surrounded by lots of german.

Ok Skypup, you can smile now and say "I told u so"

SkyPup flapping wings, ready for takeoff!

Toss that DOT 3 or pour it in Ric's fuel tank to see if it cleans out his rig and makes it run better like any of the many other things he's dumped in there

Use DOT 4 only, always, all the time!

DOT 4 is a "polyethelene glycol," just like DOT 3, but has added esters that help in raising the boiling point 63* F. more than DOT 3.

Please be kind with your responses!

I own a '96 Passat TDI wagon with 130k miles on it. I have upgraded to 15" wheels, and plan shorlty to upgrade to Corrado G60 front brake components (carriers, calipers and rotors: from 256mm to 278mm?; roughly goes from a 10" to an 11"). My car has not yet had a brake fluid flush, as I was waiting to change over the calipers and possibly add stainless steel / teflon brake lines. I know to flush the system, and replace all brake fluid once every 2 years.

Now for the part that I may take alot of heat over: I bought MANY MONTHS AGO 2 quarts of Castrol synthetic brake fluid believing it was a superior product to DOT 4 or 5. This was WAY before the "syncrap" scandal broke on this forum over that company's infamous "100% fully synthetic engine oil".

Should I use the Castrol synthetic brake fluid? If directed to use a DOT 4 product instead, is one brand better than another?

------------------
1996 Passat TDI Wagon; y2k NB TDI.
Reside in Ft. Lauderdale, FL

If you have Castrol SRF, the Castrol web site says it is DOT 4:

Castrol SRF exceeds the US Federal
Standards FMVSS 116 DOT 3 and
DOT 4, ISO 4925, JIS K2233 and
current SAE J1703 and is miscible with
all conventional brake fluids conforming
to these standards.

Use DOT 4 as it exceeds the US Federal
Standards FMVSS 116, DOT 3, ISO 4925, JIS K2233 and current SAE J1703.

DOT 3 does not even meet U.S Postal Service Standards, and we all know how slow they can be!! (Not to trash the Postal Service, I have great respect for them!).

Valios,

The US Postal service can outshoot any other postal service anywhere in the world ...now if you want a letter delivered ....

HowardZ,

My 1990 Audi (a VW product) clearly says on top of the brake reservoir to use "only DOT 4 fluid from an unopened container" This is a 10 year old car and VW/Audi was specing this quality of fluid way back then ....With ABS cars you need to use high quality fluid to keep deposits from building up and ruining your $1200.00 Bosch ABS system. But hey, it's your money ....

I believe there is a guy in Florida (no, it's not Skypup) that will buy the DOT 3 stuff from you ....

TS

If that Castrol stuff says "DOT 5", or "Meets or exceeds the requirements for DOT 5", do NOT use it in a Volkswagen brake system! If it's DOT 4, you're OK. If it's DOT 5.1, you are probably OK. If it doesn't say, don't take your chances.

-mickey

The DOT 3 can be used for other purposes. Have a power steering system thats leaking? add 2 oz. of it to the system run for a while, drain it and add fresh PS fluid presto, it will condition the seals and stop the leak. By the way brake fluid will darken noticibly from water contamination and cause clutch master cylinder and slave cylinder failure on hydraulically actuated systems. An appreciation of the US postal service comes from living in another country, in my book they are the best.

I was wrong about the synthetic brake fluid being made by Castrol. It is a Valvoline product called "Synpower." It states that it is a high performance synthetic brake fluid. Claims to be compatable with all DOT 3 & 4 systems; with a dry boiling point of 513, and a wet boiling point of 333 degrees (F). Meets or exceeds specifications SAEJ1703, FMVSS #116 & DOT 4. Claims to mix with other fluids. The bottle states: "Contains: Brake Fluid (a complex mixture of glycol ethers, polyglycols and inhibitors)." "Its premium, synthetic, low moisture formulation provides superior anti-vapor lock protection."

The following is listed for comments or questions: 1-800-TEAM-VAL & www.valvoline.com

Anyone know of this product? Again the question: should I use it? Comments?

One last question, for systems that are DOT 3 rated, is there any harm in using a DOT 4 fluid (conventional)?


------------------
1996 Passat TDI Wagon; y2k NB TDI.
Reside in Ft. Lauderdale, FL

As for kiki's last question, my 1995 H*nd@ Civic Vx's manual said: "use either DOT-3 or DOT-4 brake fluid." I don't know if that means actually mixing the 2 is O.K., but since they are made of the same polyethelene glycols, I doubt that there would be any resultant harm. Of course, such a mixture would lower the boiling point, and so would probably behave more like a DOT-3 brake fluid.

When I replaced my pads and rotors a while back is used Valvoline SynPower brake fluid. I think it's a good product for the money considering I once paid $20 for a liter of Lucas/Girling brake fluid. The Valvoline product had the same wet and dry boiling points.

Brian, 97 Passat TDI

What about this ATE (type 200)brake fluid? I quote:

Minimal decrease of boiling point due to excellent water locking properties.
Non-foaming when filling and bleeding the brake system.
Excellent corrosion protection due to selected additives.
High safety tolerance against steam bubbles.
Makes brake fluid changing intervals of up to 3 years possible.

Standards conformed to:
FMVSS No. 116 - DOT4 and DOT3*
SAE J1703
DIN/ISO 4925

Boiling point:
at least 280°C (50°C over DOT4)

Wet boiling point:
200°C (45°C over DOT4)

Can I use this?

I read a specification a few years ago that outlined the significance of 3, 4 and 5.1. These specifications generally address properties (compressibility, boiling point) and deal less with the actual chemistry of the product, but, as stated before, the DOT 5 is truly silicone-based and should not be used in a normally DOT 3 or 4 application. DOT 5.1 is truly chemically compatible with 3 and 4, but meets the boiling point requirements of DOT 5. I would not hesitate to use DOT 5.1 in any of my vehicles (except the Buell with DOT 5 from the factory).

As for the flurry of questions about this fluid or that - if it says that it meets DOT 4 requirements, you're there, as far as your DOT 4-requiring German car is concerned.

One other thought - as the former employee of a certain German brake manufacturer I can assure you that the brake components we made for the American cars (for which only DOT3 was specified, *without* any periodic fluid change requirement) were no different from what we sold to VW. The difference is in the operating environment (in which the driving is more severe and critically dependent on the brakes). Changing brake fluid is a good idea in any car. Using DOT 4 is a good idea in any car (other than the rare DOT 5 application). While it may give you the willies putting DOT3 in your VW (and it may invalidate your warrantee ) it'll be no worse off than your (fill in the blank) American car that will probably spend its entire life with the factory charge of DOT 3.

------------------

I like DOT-3 for removing paint...

I bought Valvoline High Performance Dot3 and Dot4 brake fluid today.
According to the chart in the article below, it has higher boiling points (both dry and wet) than the Castrol LMA.
Brake Fluid Comparision

I paid US$4.99 + tax for the 32oz bottle.

[ March 08, 2002, 11:41: Message edited by: rahsut ]

You can run ATE 200 and it's blue brother ate super blue. Like I said earlier, I alternate between them so the bleed is easy. It changes color and you know you have all the old stuff out of the system.