About the compatibility of different brands of brake fluid

Often motorists themselves do not know what kind of fluid is in the brake system reservoir. And when the need for topping up arises (after repairs or when bleeding the brakes), a logical question arises: what, exactly, is in the tank, and what can it be mixed with? Below we will try to briefly answer the question: is it possible to mix brake fluid from different manufacturers?

What is TJ used for?

The task of any diesel fuel in every car is to have the lowest compression ratio and calmly withstand maximum temperatures, in other words, not to start boiling at high temperatures. On average, a car can work on one vehicle for about 3 years - everything depends on the quality of this mixture, as well as on the weather outside and on general performance characteristics.

But still, sometimes every car needs to replace the brake mixture, and this may be required not only because of its deterioration in terms of performance. The need for replacement is usually caused by a break or break in the brake wire (hose), which, naturally, can go along with the leakage of the mixture. It is dangerous if this happens while the car is moving.

However, you can always go to a car dealership, but what if they do not stock the type of brake mixture that is used in your car? This raises a completely reasonable question: isn’t it dangerous to mix brake mixtures for cars from different brands or different classes? I tried my best to understand this article.

Like all the main elements of a car, it has come a long way in its development. Manufacturers experimented and came up with the ideal formula, adding various additives to TJ in order to improve their products to the level that we can see today.

At the initial stage of its development, the brake mixture had a primitive composition - mineral additives were used as its basis. After a certain period of time, manufacturing companies concluded that glycol should be the basis of TK (due to poor absorption), after which they began to use ordinary silicone as a basis. Currently, the most common types of liquids are glycol mixtures and silicone type mixtures.

Compound

Brake fluids have the following composition:

Mineral brake fluids for cars are the elders in their field. The era of brake fluids began with brake fluids based on castor oil and ethyl alcohol. Now they are produced mainly from petroleum products.

Most manufacturers use glycol as a basis, which is more versatile in use. Almost their only drawback is increased hygroscopicity. As a result, the replacement procedure has to be carried out much more often.

DOT 5 for sports and racing cars is a different story. They are made only from silicone, which is why they have such properties. But the main disadvantage of these fluids is poor absorption: when the fluid enters the brake system, it does not dissolve in the substance, but settles on the walls. Corrosion of your car's hydraulic system won't keep you waiting long. That is why it is forbidden to add silicone-containing liquids to glycol or mineral ones. It is also not recommended to mix the latter with each other. If you mix them, then the rubber cuffs of the hydraulic line will come to an end.

Advice. Mix liquids only with the same composition.

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The boiling point characterizes the duration of safe operation of the brake fluid. Due to its physical and chemical characteristics, it absorbs moisture from the outside, which reduces the boiling point. When this decrease reaches a critical level, further use of the fluid may become dangerous. Therefore, the discrepancy between the boiling point of a “dry” liquid is not as dangerous for traffic safety as the boiling point of a “wet” liquid (although these two indicators are most often related to each other). After all, over a couple of years of operation, brake fluid picks up an average of 2–4% water.

The indicator “kinematic viscosity at -40 ºС” is important primarily for countries with cold winters. The fact is that the vehicle’s hydraulic system is designed for a certain fluid viscosity. Up to a certain threshold viscosity value, the driver can effortlessly or forcefully press the brake pedal, thereby forcing the braking system to perform its functions, but at higher viscosity values ​​it will be impossible to do this.

Are modern brake fluids interchangeable?

The liquid manufacturer usually indicates on the label what other liquids its product can be mixed with. But the trouble is that the consumer, as a rule, has no idea what is in his tank. No one has tested mixed liquids, so we cannot recommend such an operation. And you certainly shouldn’t add liquids with low boiling points to a modern car. In general, a complete fluid change is always preferable and safer.

What is dry liquid and wet liquid?

Car owners who are accustomed to being interested in such issues are well aware that the performance characteristics of the brake mixture are highly dependent on the volume of water.

Based on established rules, you should only fill your car with brake mixture in which the amount of water is less than 4.5 percent. If the amount of water in the liquid exceeds this mark, then the mixture will not be able to perform its tasks due to boiling at the lowest temperatures.

Answers to frequently asked questions

• Where is DOT4 used?

  The characteristics of DOT 4 brake fluid allow it to be used in hydraulic braking systems of predominantly disc type (front and rear). Also widely used in automobile clutch system.

• What is the lifespan of DOT 4 brake fluid?

  Without changing its characteristics, DOT 4 can last 2 years, after which the boiling point will decrease and the water content will increase, and after three years it can lead to loss of brakes.

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Kinds

It is customary to divide the brake mixture, which has not yet been used, into moistened and less commonly used - dry.

By dry we mean a mixture that is stored in a freshly opened container. Since car brake mixture is tightly sealed in production when it is first opened, the driver receives a mixture that contains almost no water (if we are talking about a quality product).

By wet we mean a brake mixture that can be used, but which retains a certain amount of water. For example, if a container with such a brake mixture was opened a long time ago, the composition will begin to absorb water from the atmosphere (from the air), for this reason the brake mixture after some time will turn into a moistened one.

It is important to consider: as stated earlier, fuel that has 4.5 percent (or more) water is unsuitable for use.

Therefore, you should check your vehicle before adding it to the car. You can check the amount of water using a special device that can be purchased at car markets.

Characteristics

The Neva universal brake fluid was developed at one time for use in domestic passenger cars such as Moskvich and Zhiguli, and therefore is fully compatible with brake fluids such as Tom and Rosa. Its physical and mechanical properties are as follows:

1. The temperature range for practical use is ±50 0 C.
2. The starting boiling point is 195 0 C.
3. Kinematic viscosity, cSt, at temperatures up to 50 0 C – no more than 6.2.
4. Kinematic viscosity, cSt, at temperatures up to -40 0 C – no more than 1430.
5. Corrosive activity to other metals is insignificant.
6. The temperature at which thickening begins is -50 0 C.
7. The change in boiling point after long-term storage is ±3 0 C.
8. Flash point – 94 0 C.
9. Volumetric swelling of rubber parts at temperatures up to 120 0 C, no more than 3%.

Minor corrosion activity is possible only with prolonged contact of this brake fluid with aluminum parts.

Classification

There are several systems for dividing brake fluids: according to viscosity, according to DOT standards, boiling point. In addition, there are generally accepted standards - SAE J 1703, ISO 4925, etc.

The most common of them is gradation according to DOT standards, it consists of:

DOT3 (glycolic)

Recommended for classic cars with front brakes and rear drums.

Main characteristics:

• the boiling point in the “dry” state is not less than 205 degrees, in the “moistened” state (contains 3.5% water) - not less than 140 degrees;
• viscosity at negative temperatures (-40 degrees) – not less than 1500 mm2/s.

DOT4 (glycolic)

Used for modern vehicles with disc brakes on both axles.

Main characteristics:

• the boiling point in the “dry” state is not less than 230 degrees, in the “moistened” state (contains 3.5% water) - not less than 155 degrees;
• viscosity at negative temperatures (-40 degrees) – not less than 1800 mm2/s.

DOT5 (silicone) and DOT5.1 (glycolic)

It is used on sports cars with a fairly high temperature load.

Main characteristics:

• the boiling point in the “dry” state is not less than 260 degrees, in the “moistened” state (contains 3.5% water) - not less than 180 degrees;
• viscosity at negative temperatures (-40 degrees) – not less than 900 mm2/s.

How to spot a fake

You can identify the original Ros DOT4 brake fluid by the following characteristics.

1. Branded packaging is made of gray opaque plastic. The material is moderately pliable and does not bend under pressure. The presence of defects in casting, soldering of the canister, and mechanical damage is unacceptable. Plastics do not have colored spots.
2. The lid is made of black plastic. The part has a protective skirt; when the canister is opened, the element remains on the neck.
3. Under the plug there is a foil membrane that prevents the mixture from leaking when the container is tipped over.
4. The side strip, designed to control the remaining liquid even along the entire length, ends 3 cm before the top of the can.
5. The front sticker is printed in Russian and Ukrainian. The presence of grammatical errors and blots is strictly unacceptable. Paint overflows and unprinted areas are also excluded, unless this is provided for in the packaging design.
6. The back label is in the form of a booklet. Inside the booklet, the information on the front side is duplicated in other languages ​​of the world.
7. The top of the canister is marked with the production date. The inscription is printed with a laser - this eliminates the possibility of abrasion of the index without damaging the base material.

Interchangeability of different brands

Recommendation one: topping up brake fluid made on a different base is unacceptable and dangerous to the lives of vehicle passengers. That is, silicone or BSA cannot be added to the glycol composition and vice versa.

What is the danger: the consequences do not appear immediately, but after some time, until the material is mixed and heated as a result of the brakes being applied. A precipitate forms in the mixture and dense clots form, blocking the normal operation of the system - the brakes fail. In the best case, you will have to empty all the cylinders and pipes for thorough washing.

Now about whether it is possible to add liquid made on the same basis. It is quite permissible to dilute the glycol composition with a similar material, but with reservations:

1. It is allowed to mix glycol fluids DOT 3, 4 and 5.1 with each other, DOT 5 is a silicone material, it cannot be added.
2. If you added a glycol composition with a lower boiling point, for example, DOT 3, to the fourth series fluid, the brake system is not in danger, but upon arrival at the garage it is recommended to change the working environment. The reason is the deterioration of the properties of the mixture due to the addition of low-grade material.
3. After adding a higher class fluid, for example, the 5.1 series to the DOT 3 composition, the temperature characteristics of the mixture will improve. It is not necessary to completely change the fluid in the brake system, unless you notice suspicious deviations - pedal failures or a weak response to its pressing.

Advice. It is recommended to add brake fluid on the road only after eliminating a leak or problem causing loss of brake fluid. The exception is a minor leak, where liquid escapes in small quantities.

Like glycol, silicone compounds are also interchangeable because they are made on the same basis. The boiling point of DOT 5 and DOT 5.1/ABS is identical - 260 °C (wet material - 180 °C). There is a limitation here: it is highly undesirable to add Series 5 fluid to cars equipped with an ABS anti-lock braking system; only the “native” material is DOT 5.1/ABS.

If you find yourself in a hopeless situation and still fill the expansion tank of a car with ABS with Series 5 compound, empty the system as soon as possible when you get to a garage or car service center. The additive will not lead to an emergency and will not cause significant harm to the parts, but will shorten the service life of the rubber elements.

What to fill

Today on the market there is a huge amount of brake fluid of all classes, imported and domestic.

The main rule to follow when choosing: use only the class specified by the car manufacturer. The instruction manual should contain similar information.

If you can't find it, write the make and model of your car in the comments - we will try to help you.

What are the consequences of making the wrong choice? By pouring glycol fluid into a system designed for silicone, you run the risk (over time) of serious leaks. Rubber seals are not designed for the more aggressive glycol composition.

The same problems can be obtained by filling in the more fluid DOT-4 class 6 instead of the recommended DOT-4.

Class and required volume for replacement

Information for all vehicles in the table is obtained from operating manuals that are freely available.

What brake fluids can be mixed

Based on the above, it is worth remembering that under no circumstances should you:

• allow a composition such as DOT-5 to be mixed with any of the above, they are completely incompatible;
• connect fluids in the brake system of a car with ABS, one of which is intended for ABS, and the other is not;
• add a liquid such as DOT-3 to DOT-5.1: the resulting mixture will boil at a lower temperature;
• This is also the risk of mixing DOT-4 and DOT-3 - a decrease in the boiling point of the resulting mixture.

In case of emergency, it is allowed to add:

• DOT-4, when the system is filled with DOT-3;
• DOT-5.1 to the main DOT-3;
• DOT-5.1, when the working composition is DOT-4. The resulting mixture boils at a higher temperature than the original, which, in principle, is allowed.

It is not recommended to mix liquids produced under different brands. Each manufacturer does everything to give their product high quality by adding a variety of additives. It is difficult to predict how these liquids will behave when interacting. Whatever fluid combination you use, the first thing you need to do after suddenly adding brake fluid on the road, once you reach your destination, is to completely replace the entire mixture in the brake system. If you plan to replace DOT-4 with a newer DOT-5, the brake system will need to be flushed to eliminate any remaining obsolete fluid.

Remember, it never hurts to carry a supply of the exact brake fluid that is in your car to avoid situations where you need to take risks and mix different types of fluids.

Mixing products from different brands

When producing working compounds for automobile brakes, manufacturing plants must strictly adhere to uniform standards and comply with technical specifications. Hence the conclusion: you can mix brake fluid from different manufacturers if “native” is not available for sale. The main thing is to follow the above rules regarding diluting silicone with glycol and vice versa. Only mixing materials on different bases gives a negative result; the brand does not matter.

If the system urgently needs to be replenished on the road, and the product from the required manufacturer is not available in the store, choose a liquid from another brand on a similar basis. Lower cost is not always an indicator of low quality, so you can buy a cheaper option. If doubts begin to torment you, you will change them after returning home.

The possibility of mixing is also limited by the class of passenger vehicle. As a rule, liquids of various brands and manufacturers (but not of different chemical compositions) can be filled into budget cars without problems. The requirements for premium cars, heavy modern SUVs and sports cars are more stringent. Accordingly, the operating instructions limit the use of brake fluid to one brand, for example, DOT 5.1/ABS.

If you have just such a car, then adding another brand of fluid in case of leakage is not allowed. Theoretically, instead of 5.1/ABS, you can try to top up the fifth series silicone, get to the garage and immediately empty the system without waiting for the consequences. What such a decision will lead to in practice depends on the specific car model. It is likely that nothing bad will happen and only after 2-3 years will a car service technician changing the rubber seals in the calipers discover traces of exposure to the “wrong” fluid.

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Which one to use?

Many car enthusiasts have a question about what fluid to use, especially those who recently bought a car and received a license. It is recommended to use the specification specified in the manual supplied with the machine. If you have lost your manual, it is now easy to look up the data online.

What should I do if I don’t have the fluid listed in the manual? There are such cases. You need to know which of them are compatible with each other. Let’s say you need DOT-3, you can safely add or replace it with the highest class 4 or 5.1, but only on the same base that allows mixing. Another option is to look at its analogs (ours or imported ones) on the Internet, or ask experts who have encountered this.

For example, using silicone brake fluids when you are prescribed glycolic brake fluids is suicide. Why can’t I use different brands of substances? It’s just that all rubber bands and mechanisms, cuffs, are designed for this type of chemicals; using a different type will cause destruction of the cuffs and seals, leakage and failure of the braking system.

Mixing brake fluid based on silicone and glycol is also prohibited; the difference in composition can cause coagulation and clogging of the system, and this also means brake failure. Serviceable brakes save lives, (and not only yours) remember this.

The use of a lower class of fuel fluid (the third pillbox instead of the fifth, for example), with a reduced boiling point is not desirable, because the calipers heat up, sometimes very much, and if the composition boils, the brake pedal will fail and the car will not stop in a timely manner.

Are pillbox substances from different manufacturers compatible? Yes, they are compatible, the fact is that the DOT marking means a production and composition standard. That is, in fact, manufacturers produce the same substances, according to the standard, provided that it is not a fake.

Mix from different manufacturers

And lastly, is it possible to mix different manufacturers? YES OF COURSE YOU CAN, why not? After all, there is STRONG standardization here, so DOT4 from completely different companies is interchangeable, because they must have the same base and temperature characteristics.

Of course, if it's not a fake! Still, branded fluids from the manufacturer themselves, purchased from a dealer, slightly guarantee quality, and you don’t need that much of it, only 0.5 - 1 liter, once every 2 - 4 years.

YES and remember - this liquid keeps you alive! AND THIS IS THE MOST IMPORTANT THING!

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Due to system leaks and brake malfunctions, car enthusiasts often have to add working fluid to the required level. The situation is aggravated when such things happen on the road - few drivers carry a reserve in the trunk for topping up. As a result, you need to buy and mix brake fluid from different brands and manufacturers to get it to the garage. This raises the question of the interchangeability of different compositions, which deserves detailed consideration.

Is it possible to use brake mixtures of different classes?

As you yourself understand based on the text, brake mixtures can differ significantly from each other in terms of the internal “base” - this “base” can be glycol or silicone, and other differences can only be characterized by the list of additives used.

From this we can conclude that the brake fluid is DOT 3/4/5. 1 is made on the basis of glycols. They can be mixed with each other, but it is worth highlighting that when mixed, the brake fluid changes its composition to a lower-grade one, that is, it inherits the rights of a composition with worse performance properties. This means that if you mix DOT 3 and 5 liquids, you will have a DOT 3 boiling point.

Considering the much higher cost of the higher level brake mixture, such mixing is impractical and can only be used in rare cases.

DOT 5 and DOT 5. 1/ABS. These mixtures are made on the basis of silicone, they can also be mixed with each other in rare cases, but this should not be done, since the compositions of these mixtures are strikingly different.

It is also important to highlight that you can find out information about the brake mixture used in your car in the book on its operation. It is worth following the manufacturer's recommendations and trying to use the brake mixture at the level recommended by the manufacturer.

Important: you should not mix brake fluids that are based on glycol and silicone with each other. This oversight can lead to serious financial expenses to eliminate the consequences and cause damage to the car’s brakes.

Why is it important to change

Brake fluid is very hygroscopic. During operation, intensive absorption (absorption) of moisture occurs.

The critical level of moisture content is 3.5%. With this amount of water, the boiling point of DOT-4 decreases from 230 to 150 degrees. The liquid absorbs this amount of moisture in about 2 years of operation. Therefore, manufacturers recommend replacement at least once every two years, or after 40 thousand mileage.

An exception is DOT-5, its service life is 10-15 years, since silicone is slightly hygroscopic.

Large amounts of moisture promote the development of corrosion inside the brake system. Suffice it to remember how difficult it is to unscrew stuck fittings on the cylinders when bleeding the brakes.

But the hygroscopicity of the “brake” also has its advantages.

Water is heavier, and if it were not absorbed by the liquid, it would settle at the lower points of the system and freeze there. This could lead to complete failure of the braking system.

Russian analogues

Let's look at the Russian analogues for Neva and Tom brakes, and whether they can be mixed with each other and with derivatives of the DOT classification:

• Neva, familiar to many, is produced on the basis of glycol with polyester. It also contains an anti-rust additive. However, the disadvantage is the rapid accumulation of water in it (hygroscopicity), which reduces its characteristics and requires more frequent replacements than others, is considered obsolete, and is gradually going out of production.
• Tom liquid contains glycol ether and a set of additives. Its performance is higher than that of Neva. In terms of quality and composition, it meets the DOT-3 class.
• The same base allows you to mix them with each other, replace the Neva with Tom. In addition, Tom can be mixed with other liquids of the dot-3 class and higher that have a glycol base.
• But can Neva be mixed with Dot 4? It is possible, this has been tested by experience and in practice by many motorists. Only this mixture, due to the fault of the Neva, requires more frequent changes, reducing the time by almost half. Agree, it will be cheaper to completely replace the Neva with a more reliable and long-term analogue.

Brake fluid does not enter the cylinder

He cannot log out of the system on his own. Let's say there is no brake fluid in the system; it needs to be refilled. Brake fluid is poured into the expansion tank of the brake master cylinder, which is located under the hood of the car. The tank will fill completely. But the fluid will not even get into the master brake cylinder. Because the air in the system does not allow this to be done. Attempts to push the liquid using the pedal also lead to nothing.

The brake pedal does not encounter fluid resistance and moves back and forth freely without effort. In this case, the liquid must be filled into the system in stages. First, the brake master cylinder is filled. Then the brake pipes and brake wheel cylinders. In order to fill the main brake cylinder, it is necessary to unscrew the fittings of the pipes coming from it. This will allow the brake master cylinder to fill with fluid.

It is enough just to unscrew the fittings and press the pedal several times so that the liquid begins to flow from under the tubes. It also happens that even in this case the liquid does not flow into the cylinder. Then it is necessary to bleed the cylinder. To do this, tighten the fittings back and press the brake pedal several times. While holding it pressed, unscrew the fitting again. Air will begin to be squeezed out of the master cylinder. Without releasing the pedal, screw the fittings back. Perform this procedure several times until a noticeable force appears on the brake pedal.

Even if the fluid fills the master brake cylinder on its own into the pipes and the working brake cylinders, it does not get there, you can try to unscrew the fittings intended for bleeding the cylinders and wait until the fluid begins to flow out of them under its own weight. This will take a lot of time. and you still won’t be able to achieve the desired result. The main goal is to completely remove air from the system. Because even minor air pockets in the tubes and cylinders will make the brake system inoperable. Therefore, the system must be pumped until the air is completely removed from the system.

Why does brake fluid leak?

The answer to the question is it possible to add brake fluid without bleeding if the fluid has completely left the expansion tank and the brake system is in working condition. The system definitely requires not only pumping but also preliminary repairs.

The system can lose such a volume of liquid only if there is a leak. As a rule, wear of the cuffs in the working cylinders leads to such a loss. In this case, the liquid flows onto the wheels and is visible from the inside. But the brake pipe may break as a result of some kind of mechanical stress or corrosion. You need to find the location of the fluid loss.

It will usually be noticeable by the leaking liquid. If the problem is in the tube, it must be replaced completely. If the problem is in the working cylinder, then it is also advisable to completely replace it. It is possible to repair the brake wheel cylinders by replacing the cuffs with new ones. But as a rule, this repair either does not give any result. Or it briefly extends the life of the cylinder. And then you still have to replace it with a new one. Because in addition to the cuffs, both the piston and the internal cavity of the cylinder wear out.

Installing a new cuff due to wear of the working surfaces in the cylinder itself does not lead to the desired result. Still, it is better to replace the working cylinder with a new one. And at the same time the brake pads. Then as they wear out, the stroke of the cylinder increases. The cuffs begin to wear out rapidly. After repair, the brake system definitely needs to be bled.

Checking the brake fluid level

Is it possible to add brake fluid without bleeding if there is fluid in the expansion tank but its level has decreased? Yes, in this case there is no need to bleed the system. But the system still needs to be carefully inspected. Liquid leaks are possible but not significant. Which will subsequently lead to more serious damage. It is better to detect the malfunction at the initial stage.

The level of brake fluid in the expansion tank drops, even if the brake system is working properly, as a result of wear of the brake pads. The greater the wear, the greater the stroke of the cylinders. The greater the volume of liquid fills the system. When worn, the pads begin to move away from the working cylinders. Therefore, a larger volume of liquid must be supplied to the cylinders. But the piston stroke of the brake master cylinder may not be enough to push through the required volume.

Security measures

To prevent brake fluid from oxidizing, evaporating, or picking up moisture, it must be stored in an airtight container.

As a rule, they are flammable, so they must be kept away from open flames and high temperatures.

They are poisonous, it is recommended to work with gloves, although there will be no obvious signs of burns if they come into contact with the skin.

Under no circumstances should you drink, even a small amount will lead to poisoning. If liquid gets into your eyes, rinse them thoroughly with clean water and consult a doctor.

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How often to fill brake fluid

It has already been said above that all regulations for servicing your vehicle, as well as the timing for replacing working fluids, are specified by the vehicle manufacturer. If we talk about the replacement interval, on average it is 40–60 thousand kilometers, or 2-3 years of car operation. It is recommended to rely specifically on the information in your manual, and not on what is indicated by the manufacturer on the packaging.

The numbers on the label can be a marketing tool of an unscrupulous manufacturer to attract buyers.

You should not exceed the recommended periods, and if the car is actively used, it is better to fill in fresh fuel oil more often. This procedure is quite inexpensive, and if you do it yourself it becomes even cheaper.

Every car owner should know where to fill the brake fluid in his car, and before setting off on the road, he should definitely evaluate the external condition of the brake fluid, the color and level in the expansion tank, and top up the brake fluid if necessary. A sharp decrease in level indicates that there is a leak in the system, possible rupture of brake hoses, pipelines, and wear of the seal in the brake cylinders.

If a malfunction is detected, it is strictly not recommended to operate the vehicle; it is necessary to eliminate the cause of the leak and it is advisable to fill in a new fuel fluid, since dirt could get into the system through the leak.

The condition of the vehicle is also monitored during a technical inspection of the vehicle, when oils are changed and minor urgent repairs are performed; most often this procedure occurs in the off-season.

The expansion tank is marked with minimum and maximum levels, which indicate how much brake fluid to fill. It is very important to adhere to this range, do not allow the level to drop below and not overfill above the indicated marks. Failure to comply with this point may result in airing of the system or overflow of excess fluid through the valve of the expansion tank. When traveling long distances, it is advisable to have a small supply of fuel fluid in the car so that, if necessary, you can fill in the missing amount.