Types and properties of brake fluid, compatibility. How to replace

What is brake fluid? This is a special substance to ensure car braking. It is in liquid state and presses on the brakes after pressing the pedal. In other words, it provides a link between driver teams and brake mechanism. If there is a violation of this connection, the car simply will not stop. This may happen in the case of excessive heating of the fluid, after which steam appears inside the brake mechanism. It makes the system of compressible, and the substance will not be able to tie down on the pedal with a sharp slowdown and a blow on the brakes. That is why the brake fluid is although a small, but very important piece of car. Without it, the driver will not be able to move in the stream. In other words, there is no brake fluid - no brakes.

The brake fluid is divided into several species that differ in the temperature of its heating. So, the first classification separates this substance on the "moisturized" and "dry" fluid. Naturally, the "dry" fluid includes less waterAnd in the "moistry" its share is 3-4%. Moreover, these two brake fluids are divided into four groups: dot 3, dot 4, dot 5 and dot 5.1. The very first type withstands the smallest temperature: 205 degrees Celsius for "dry" and 140 - for "moisturized". It follows DOT 4 (for machines with heavy loads require a greater temperature, and therefore the second type of brake fluid is designed for 155 and 230 as for DOT 5.1 liquid, it can be found on sports cars, for example, on BMW M6, Ferrari F458, and Others. But the penultimate view of the mass machines is almost no applied. Most likely, Dot 5 is put on and finalized modifications of sports cars. By the way, it is possible that it is worth the most perfect liquid. Outstanding characteristics confirm this.

So, we considered the types, but the question remains "what braking fluid is better?". How to answer it? Of course, the best braking will provide DOT 5. As for serial cars, then it is dot 5.1. The remaining types of liquids are more suitable for ordinary conditions and standard carswhich are not designed for huge speed and

Summing up, I want to pay attention to the components from which the brake fluid consists. The composition of this substance is a diversity of this substance. For example, silicone brake fluid contains polymers, and glycohel consists of polyglycol. But they have something common - additives. These include anti-corrosion and lubricants.

What is the main function of the brake fluid? Of course, this is security during the movement of the car. As mentioned above, there are no brakes without this substance. Therefore, it is important to treat it with special attention, because the leak can lead to dangerous consequences. Nothing good will and use DOT 3 liquid on sports carsAfter all, large overloads lead to its excessive heating.

It should be noted that mixing different liquids You can, if only they are on one basis. If there is no appropriate information on the label, it is not worth risking!

Brake fluid is a type of hydraulic fluid that is used in hydraulic brake systems and hydraulic clutch systems on cars, motorcycles, light trucks, as well as bicycles. Liquid is used to transmit pressure and to enhance brake force.

General information about brake fluid

The principle of operation of the brake fluid is its small compressibility. Molecules do not have internal emptiness, so when compressed, the volume of the fluid does not decrease, and the pressure quickly applies to the entire volume.

The composition of the brake fluid

The brake fluid is different, but it is usually produced from a low-viscous solvent, for example, alcohol, and viscous non-volatile substance, for example, glycerol.

Based on polyethylene glycol produce brake fluid under the brands DOT 3, DOT 4 and DOT 5.1.

Based on silicone - silicon-organic polymer products Mark DOT 5.

For vehicles with anti-lock system, brake fluids DOT 5.1 / ABS based on silicone and glycols can be used. About brake fluids Wiki: link.

Characteristics and properties of brake fluid

In order for the brake system to work properly, the brake fluid should have certain characteristics and respond to quality standards.

Boiling temperature. The new brake fluid does not contain moisture, so its boiling point is in acceptable limits. But over time, the moisture from the ambient air falls into the fluid, usually 1-2% per year from the total volume, but the characteristics of the brake fluid begin to change.

During braking, the working fluid heats up to very high temperatures Due to friction. At this point it is very important that the braking fluid does not boil, since in this case the moisture evaporation from the liquid in the form of steam occurs. And the steam is dangerous in that it is easy to compress and, with the next braking, the pressure on the brake will be less, since part of the volume will take a compressible pair.

The boiling point of the brake fluid directly depends on the amount of water in it. The more water, the lower the boiling point and the greater the chance of "losing" the brakes.

Gigroscopic. Some brands "TORROSUCHU" have minimal hygroscopicity (moisture absorption), for example, DOT 5 and can save throughout the service life necessary characteristics. But the most common stamps Dot 3, Dot 4 and Dot 5.1 gradually lose their properties due to an increasing number of moisture in them.

Viscosity. This characteristic will depend on how the brake fluid will be pumped throughout the system. And it should be swept away well and at -30 degrees Celsius and at 200 degrees, during braking.

If the liquid freezes completely or in some places, it blocks the operation of the brakes. Too thick liquid will hardly be pumped throughout the system, which will lead or to bad braking or different effort on different wheels. And too liquid will lead to the appearance of the leaks.

Corrosion protection. The brake fluid itself acts as protection against corrosion inside the brake system. In this case, protection should be ensured even with small amounts of moisture inside the system.

Corrosion protection is ensured by special additives. They also provide protection for sealing elements.

Compressibility. Ideally, the brake fluid should not compress much, but there are certain tolerances for this characteristic. The main thing is that the fluid is equally well working under different temperature conditions.

Compatibility of brake fluids

For the topping, you can use the liquid of the same manufacturer, but subject to the principles:

• you can add only liquid with a higher rating digit, that is, DOT 4 can be pouring in Dot 3, and DOT 5.1 can be cast in Dot 4.
• Do not mix DOT 5 with other brands - DOT 3, DOT 4, DOT 5.1.
• You can not mix mineral (for example, LHM +) and glycol fluids.

If you break the rules, it will lead to a serious change in fluid characteristics for the worse.

How often change brake fluid

To the question when changing the brake fluid can be answered uniquely: once every two years or after 40,000 mileage. These are general recommendations.

If the car is operated in harsh conditions, then change the brake fluid is more often.

The usual topping cannot fully compensate for changes in the properties of the liquid - the boiling point drops, the chemical composition changes, anti-corrosion additives work worse. It is possible to use the method of teller only when repairing or in case of leakage, when you just need to get to a hundred or garage.

You can define an unsuitable brake fluid:

• With the help of complete analysis using special equipment.
• "On the eye" - the old liquid of dark color, while the new translucent.
• Using the device determining the amount of moisture in the liquid. If less than 3.5 percent, you can still ride.

Pour the brake fluid is necessary in expansion tank brake system. It is usually located above the main brake cylinder and serves to compensate for the brake fluid when it is heated, as well as to prevent entering the air.

The level of fluid in the tank should be between MIN and MAX marks. In modern cars there is a float with a sensor, which will notify the driver that the level of fluid in the tank fell below the minimum mark.

How to replace brake fluid

It is best to do it on specialized hundred. Most modern cars It has aBS systemAnd it imposes its mark on the procedure. Equipment is necessary for pumping the system with a new liquid.

If you are told that you can replace the brake fluid without pumping without special equipment, then do not listen to these tips. Yes, on some wheels, pressure from the tank can be slowing the system, but it will not work so much. As a result, the system will remain air or old liquid. For a hundred, the replacement of the fluid is produced under pressure, so the subsequent pumping is not required.

The replacement procedure itself is as follows. In an empty expansion tank, the cooling system is poured a new liquid, after which the pump occurs on each highway, during which the new liquid displaces the old.

The brake fluid volume on average ranges from 0.75 to 1.3 liters.

Vividly replacing the brake fluid without special equipment is described in the video below:

Prices of brake fluids

Usually, Dot 4 brake fluid prices range out around 600-700 rubles per 1 liter. Some manufacturers are asking for 1,500 rubles for a similar brand.

DOT 5.1 costs from 1 100 rubles, depending on the manufacturer.

Security measures

So that the brake fluid is not oxidized, did not evaporate and did not gain moisture, it is necessary to be stored in a hermetic container.

As a rule, combustion, so it is necessary to keep them away from the open flame and high temperatures.

In no case can not drink, even a small amount will lead to poisoning. If the fluid gets into the eyes, it is necessary to thoroughly rinse them with clean water and turn to the doctor.

One of the most important for the normal operation of the vehicle is brake. What is needed by this fluid, with which periodicity it requires replacement and which brake fluids are used to optimally work the brake system of the machine - in our current article.

The role of brake fluid in the "body" auto

The brake system responsible for the timely stop of the car and therefore plays an important role for the safety of passengers of the machine, cannot work without braking fluid (TK). It is it that performs the main function of the brake system - transmits through the hydraulic drive the force from pressing the brake pedal to the brake mechanisms of the wheels - shoes and disks, as a result of which the car stops. Therefore, in the driving slices, novice motorists strongly recommend periodically checking the levels of four service fluids:, glass cleaner and brake fluid, on which the optimal operation of the machine depends.

The composition and properties of brake fluids

The basis of the chemical composition of the majority brake fluids is polyglycol (up to 98%), less often manufacturers use silicone (up to 93%). In brake fluids that were used on soviet carsThe basis was mineral (castor oil with alcohol in a 1: 1 ratio). Use such liquids in modern cars is not recommended due to their increased kinetic viscosity (thick at -20 °) and low boiling point (at least 150 °).

The remaining percentages in the polyglycol and silicone TK are represented by various additives that improve the characteristics of the brake fluid base and perform a number of useful functions as the protection of the surfaces of the working mechanisms of the brake system or prevent the oxidation of TK as a result of the exposure to high temperatures.

We did not stop in vain in vain on the chemical composition of brake fluids used in cars, since many motorists are interested in the question - "Is it possible to mix TK with different chemical bases?". Respond: Mineral fluids for the brake system are categorically not recommended to be mixed with polyglycolic and silicone. From the interaction of the mineral and synthetic bases of these liquids, clots of castor oil can be formed, which are clogged by the brake system, and this is fraught with the brake system faults. If mixed mineral and polyglycolic TK, then this "hellish mixture" is absorbed into the surface of the rubber cuff parts of the hydraulic drive of the brakes, which will lead to their swelling and loss of sealing.

Polyglycol TK although they have a similar chemical composition, and can be interchangeable and, but not recommended to mix them in one brake system. The fact is that each manufacturer of TK can change the composition of additives at its discretion, and their mixing can lead to a deterioration in the main performance characteristics. working fluid - viscosity, boiling point, hygroscopicity (ability to absorb water) or lubricating properties.

Silicone brake fluids do not mix With mineral and polyglycolic, since the resulting working medium is clogged with chemicals falling into precipitate, which will lead to clogging of the brake system highways and the failure of the brake cylinder nodes.

Classification of brake fluids

Today, in most countries of the world, there are uniform brake fluids, known as DOT (by the name of the departments, which developed - Department of Transportation - the Ministry of Transport of the United States of America) - such labeling can be often found on packaging with brake fluids. It means that the product is manufactured in accordance with the regulatory federal standards for the safety of FMVSS vehicle No. 116 and can be used in brake systems of passenger and trucks depending on the technical characteristics These vehicles. In addition to the American standard, brake fluids are marked in accordance with the norms adopted in a number of European and Asian countries (ISO 4925, SAE J 1703 and other).

But they all classify brake fluids in two parameters - their kinematic viscosity and boiling point. The first is responsible for the ability of the working fluid to circulate in the mains of the brake system (hydraulic drive, tubes) at extreme operating temperatures: from -40 to +100 degrees Celsius. The second is to prevent the formation of the steam "plug", which is formed at high temperatures and can lead to the brake pedal to be triggered at the right time. When classifying the TK on the boiling point, two of its conditions differ - the boiling point of the liquid without water impurities ("dry" TK) and the boiling point of a liquid containing up to 3.5% water ("moisturized" TK). "Dry" boiling point of the brake fluid is determined by the new, just a flooded working fluid that did not have time to "dial" water and therefore has high operational characteristics. "Moisturized" boiling point TZ refers to the working fluid, which is operated for 2-3 years and contains a certain amount of moisture. Read more about this - in the section "Terms of operation of brake fluids". Depending on these parameters, all brake fluids are divided into four classes.

Dot 3."Dry" boiling point in this brake fluid is at least 205 °, and "moisturized" - at least 140 °. The kinematic viscosity of such TK is + 100 ° - no more than 1.5 mm² / s, and at -40 - at least 1500 mm² / s. The color of this brake fluid is light yellow. Application: Designed for use in cars, maximum speed Movement of which is no more than 160 km / h, in the brake system of which are used disk (on the front axle) and drums (on rear axis) Brakes.

DOT-3.

DOT 4. "Dry" boiling point in this brake fluid is at least 230 °, and "moisturized" - at least 155 °. The kinematic viscosity of such a TK is + 100 ° - no more than 1.5 mm² / s, and at -40 - at least 1800 mm² / s. The color of this brake fluid is yellow. Application: Designed for use in vehiclesThe maximum speed of which is up to 220 km / h. In the brake system of such cars installed disk (ventilated) brakes.

DOT 5. "Dry" boiling point in this brake fluid is at least 260 °, and "moisturized" - not less than 180 °. The kinematic viscosity of such a TK is + 100 ° - not more than 1.5 mm² / s, and at -40 - at least 900 mm² / s. The color of this brake fluid is dark red. In contrast to the above TK in the Dot 5, the base is silicone, and not polyglycol. Application: Designed for use on special vehicles operating under conditions of extreme for brake temperature systems, and therefore on ordinary passenger cars not used.

"Dry" boiling point in this brake fluid is at least 270 °, and "moisturized" - at least 190 °. The kinematic viscosity of such a TK is + 100 ° - not more than 1.5 mm² / s, and at -40 - at least 900 mm² / s. The color of this brake fluid is light brown. Application: Designed for use in sports brake systems racing carsin which the temperature of the working fluids reaches critical quantities.

Pros and Cons Brake Liquids

All the above brake fluids have their advantages and disadvantages. For convenience, specify them in the table below:

When to change brake fluid?

The timing of the brake fluid is directly dependent on its chemical composition.

Mineral TK due to its chemical characteristics (low hygroscopicity, good lubricating properties) has quite prolonged exploitation (up to 10 years). But when it gets into a liquid of water, for example, in case of depressurization of the brake system, its properties change (the boiling point drops, the viscosity increases), and it can no longer perform its functions, which can lead to the failure of the brakes. Periodic examination (once a year) of the brake system and the state of the liquid, which can be determined in the laboratory conditions.

The polyglycolic TK has an average or high degree of hygroscopicity, and therefore the test of its condition should be carried out twice a year. It is possible to evaluate the state of the polyglycol TK, visually: if the liquid has darkened or precipitation is noticeable, then it is necessary to carry out full replacement. In the year, such TK is capable of absorbing up to 3% moisture. If this indicator exceeds 8%, the boiling point of the brake fluid may fall to 100 °, which will lead to the boiling of the TK and the output of the entire brake system. Car manufacturers It is recommended to change the brake fluid based on polyglycols every 40 thousand kilometers or every 2-3 years. Typically, such brake fluid is completely changed during the installation of new external brake mechanisms (pads and discs).

Silicone TK is distinguished by the durability of operation, since its chemical composition is more resistant to external influences (moisture intake). As a rule, the replacement of silicone brake fluids is carried out after 10-15 years since the fill in the brake system.

Brake fluid The most important consumable component in the auto system. For what purposes is the brake fluid, when to replace and what better to use the liquid to read in the article.

Purpose of brake fluids

Transmit effort from the main brake cylinder to the wheel. The task is though narrow, but extremely responsible; The braking system has no right to refuse under any circumstances. When in hydraulic drive Brakes The fluid does not suit, attention to it seemingly not need to pay. However, the efficiency of braking and stability of the system depends on its state. If, for example, bad antifreeze or motor oil Only reduce engine life, the low quality of the brake fluid can lead to an accident.

The brake fluid (TZH) consists of the base (its share of 93-98%) and various additives (the remaining 7-2%). Outdated liquids, such as "BSK", made on mixtures of castor oil and butyl alcohol in proportion 1: 1. The basis of the modern, most common, including ("Neva", "Tom" and Romdot, it is "dew"), - polyglycols and their esters. Silicones are much less likely. In the additive complex, one of them prevent the oxidation of the air of the air oxygen and with strong heating, while others protect the metal parts with corrosion hydraulic parts. The main properties of any brake fluid depend on the combination of its components.

Boiling temperature. What it is higher, the less likely to form a steam plug in the system. When braking the car, workers cylinders and liquid are heated in them. If the temperature exceeds the permissible, the TJ will boil, and steam bubbles are formed. The incompressible fluid will become "soft", the pedal will "fail", and the machine will not stop on time. The faster the car was driving, the more heat is highlighted when braking. And the more intense deceleration, the less time will remain on the cooling of the wheel cylinders and the supply tubes. This is characteristic of frequent long-term braking, for example, in mountainous areas and even on a flat highway loaded by transport, with a sharp "sports" car control style. Sudden boiling of the DSA is insidious that the driver cannot predict this moment.

Viscosity characterizes the ability of fluid to pump through the system. Temperature ambient And the TJ itself can be from minus 40 ° in winter in the unheated garage (or on the street) to 100 ° in the summer in motor compartment (In the main cylinder and its tank), and even up to 200 ° C with intensive slowing down the machine (in working cylinders). Under these conditions, the change in the viscosity of the fluid must correspond to the cross sections and gaps in the details and nodes of the hydraulic system specified by the car developers. Frozen (all or in places) The TJ can block the operation of the system, thick - it will hardly be pumped through it, increasing the time of triggered brakes. And too liquid - increases the likelihood of leaks.

Impact on rubber parts. Seals should not swell in the TJ, reduce their dimensions (give a shrinkage), lose elasticity and strength more than it is permissible. The swollen cuffs make it difficult to reverse the pistons in the cylinders, so it is not excluded to carry out a car. With the following seals, the system will be lenked due to leaks, and slowing - ineffective (when the pedal is pressed, the fluid flows inside the main cylinder, without transmitting the force of the brake pads).

Impact on metals. Details made of steel, cast iron and aluminum should not be corroded in the DJ. Otherwise, the pistons "scatter" or cuffs operating on the damaged surface are rapidly wear out, and the liquid flows out of the cylinders either will be pulled out within them. In any case, the hydraulic drive stops working.

Lubricating properties. To cylinders, pistons and cylinders of the system are less wearing, the brake fluid should lubricate their operating surfaces. Scratches on the cylinder mirror provoke the leaks of the DJ.

Stability - Resistance to the effects of high temperatures and oxidation of air oxygen, which is faster in the heated fluid. Oxidation products of the TJ corrosive metals.

Gigroscopic - The tendency of brake fluids on a polyglycol-based basis to absorb water from the atmosphere. In operation - mainly through the compensation hole in the tank lid. Brake fluid has one unpleasant property: it absorbs moisture. Because of the permanent drops of temperature, condensate is formed in it. The greater the water dissolved in the DJ, the earlier it boats, the thickness is thick low temperaturesThe details are worse, and the metals in it are corroded faster. The presence of only 2-3 percent of water in the brake fluid reduces its boiling temperature by about 70 degrees. In practice, this means that when braking Dot-4, for example, it will boil, without warming up and up to 160 degrees, while in the "dry" (that is, without moisture) it will occur at 230 degrees. The consequences will be the same as the air in the brake system: the pedal becomes a stake, the braking force loosely weakens.

Brake fluids classes

When developing liquids, as a rule, focus on the requirements of the American FMVSS Car Safety System No. 116 (DOT). The fluids are classified by boiling and viscosity temperature (see table), the remaining properties are close.

What kind of TJ should be applied in the car, solves its manufacturer. The brake system of the car (including rubber and structural materials) is developed under a certain type of brake fluids, so domestic fluids should not be used on foreign cars - and not because our worse, and imported better. Just every machine is made of its materials, and different DJs can affect them. The main rule of the use of brake fluid is to follow the recommendations of the instruction attached to the car.

Dot 3 liquids are designed for drum brake hydraulic drive, as well as for disk brakes under normal operating conditions. Dot 4 type fluids are used on cars with disk brakes operating in urban environments (in "Acceleration-braking" modes). Alcohol-Castor liquid "BSK" can not be considered as a DJ for modern cars. It was designed for old cars of the Times of GAZ-21 and freezes at a temperature of 20 ° C. Liquid "Neva" brand "A" slightly inferior to the requirements of the DOT 3, and the brand B "- does not correspond to them on the boiling point as dry, so and moisturized liquid. TZH "Neva" was designed for use in the brake systems of the first models "Zhiguli". Brake fluids DOT 3, "Tom" and Dot 4 can be applied almost at all domestic cars.
The DOT5 brake fluid is also known as the "silicone" brake fluid ("Silicone"). Its advantages: Does not corrosive paint; does not absorb water and can be useful where absorption is a problem; It is compatible with any rubber parts. Disadvantages: Dot5 can not be mixed with DOT3 or DOT4. Most problems with DOT5 occur probably due to mixing with some other types of brake fluid. Best way Go to Dot5 is the full bulkhead of the hydraulic system. Complaints that Dot5 leads to the failure of the rubber parts of the brakes, they are inherent in the early formulas (compositions) DOT5. It was believed that the reason for this was the inappropriate use of various additives. In the latest formulas, this problem has been eliminated. Since Dot5 does not absorb water, any moisture located in hydraulic systemwill accumulate in one place. This can cause local corrosion in hydraulics. Careful pumping is needed to remove all air in the system. Small bubbles can be formed in the liquid, the size of which increases over time. It may take several pumping. Dot5 is a somewhat compression (which gives a barely noticeable feeling of the "soft pedal"). Boiling point DOT5 is lower than that of DOT4.

Brake fluid Dot5.1 is relatively new, so it constantly introduces motorists to delusion. This error could be avoided if this brake fluid would be called differently. The designation "5.1" can assume that it is a modification of the brake fluid DOT 5 on a silicone basis. It would be more natural to call it 4.1. or 6, since Dot5.1 has a glycolic basis, as well as Dot3 and Dot4, and not silicone like Dot5. As for the fundamental nature of the brake fluid 5.1, it can be determined as "high-tech" DOT4 brake fluid than traditional DOT5. Its advantages: Dot5.1 provides excellent work, compared with other brake fluids, which are discussed in this article. She has a higher boiling point, compared to Dot3 or 4, both the initial and ultimate. In fact, the final boiling point (about 275 degrees C) is almost the same as in racing brake fluids (about 300 degrees C), and the initial boiling point of the brake fluid 5.1 (approximately 175-200 degrees C) is naturally significantly higher than that of racing brakes liquids (about 145 degrees). It is believed that Dot5.1 is compatible with any rubber components.

Disadvantages: Dot5.1 - not silicone brake fluids, therefore, they absorb water. Dot5.1, like Dot3 and Dot4, corrosive paint. Class 5.1 liquids that do not contain silicone are sometimes denoted as a DOT 5.1 NSBBF, and silicone dot 5- dot 5 SBBF. NSBBF abbreviation means "non Silicon Based Brake Fluids" ("Brake fluid, not based on Silicone"), and SBBF - "Silicon Based Brake Fluids" ("Silicone Blowed Liquid").

Features of operation of brake fluids

The absorption of water from the atmosphere is peculiar to the TJ on a polyglycol-based basis. At the same time, the temperature of their boiling is reduced. FM VSS normalizes it for "dry" that have not yet scored moisture, and moisturized, containing 3.5% water, liquids - i.e. Limits only limit values. The intensity of the absorption process is not regulated. The TW can be saturated with moisture first actively, and then - slower. Or vice versa. But even if the values \u200b\u200bof the boiling temperature in the "dry" fluids of different classes make close, for example, to the DOT 5, with their moisture, this parameter will return to the level peculiar to each class. The TJ should be replaced periodically without waiting for its condition to get closer to the dangerous limit. The lifespan of the liquid assigns the automotive plane by checking its characteristics in relation to the features of the hydraulic systems of their machines.

Checking the state of the fluid

Objectively, determine the basic parameters of the DUE can only be in the laboratory. In operation - only indirectly and not all. Self-liquid checked visually - appearance. It should be transparent, homogeneous, without precipitation. In addition, in car services (mainly large, well-equipped, serving foreign cars), its boiling point is estimated by special indicators. Since the liquid in the system does not circulate, in the tank (test location) and its properties can be different in the wheel cylinders. In the tank, it in contact with the atmosphere, gaining moisture, and in brake mechanisms - not. But there, the fluid is often and strongly heated, and its stability deteriorates. However, even such indicative checks should not be neglected, there are no other operational control methods.

Compatibility and replacement

The TZ with different bases are incompatible with each other, they smell, sometimes a precipitate appears. The parameters of this mixture will be lower than any of the initial fluids, and the influence of its rubber parts is unpredictable. The basis of the manufacturer, as a rule, indicates the packaging. Russian RosDot, "Neva", "Tom", as well as other domestic and imported polyglycol fluids DOT 3, DOT 4 and DOT 5.1, can be mixed in any proportions. The DOT class 5 is based on silicone and are incompatible with others. Therefore, the FM VSS 116 standard requires staining "silicone" fluids into a dark red color. The remaining modern DZH is usually yellow (shades from light yellow to light brown). For additional checks, you can mix the liquid in proportion 1: 1 in the glass container. If the mixture is transparent and there is no precipitate, the DVG is compatible. It should be remembered that mixing liquids of different classes and manufacturers is not recommended, since it is possible to change their properties. It is forbidden to mix glycol fluids with castor. Adding fresh fluid when pumping the system after repair does not restore the TJ properties, because almost half it does not change. Therefore, in the time limits installed by the automobile plant, the liquid in the hydraulic system must be replaced completely.