A good DOT 4 brake fluid must meet certain requirements and conditions, the main one of which is a high boiling point. If this condition is not met, the brake pedal will fail, which can lead to negative consequences.
The second point is to protect the brake system from corrosion. The appearance of signs of wear and corrosion causes a decrease in the performance of this system.
The third condition is the lubricating properties of the brake fluid. This characteristic is especially important for vehicles equipped with ABS, since such systems use only DOT 5.1 fluid.
The last requirement is to maintain a constant fluid viscosity. If this parameter deviates from the norm, then the car’s brake elements will freeze in the cold season. Which DOT 4 brake fluid is better and what to rely on when choosing it, we will consider in this article.
Composition of DOT liquid
DOT is the abbreviated name of the US Department of Transportation, which is responsible for the safety of operation and movement on any rolling stock, including cars. Recommended requirements for brake fluids were developed and proposed by this very structure. The generated requirements were divided into several classes:
- DOT 3;
- DOT 4;
- DOT 5;
- DOT 5.1.
The first two classes are based on polyesters of boric acid and polyethylene glycol; the third class is distinguished by a silicone base. In addition to the listed substances, the composition includes additives that impart certain technical characteristics to brake fluids.
Liquids of classes DOT 3, 4 and 5.1 are interchangeable, however, experts recommend using only those compositions that are indicated in the vehicle’s technical data sheet. Brake fluid labels also indicate compatibility with other product classes.
For cars equipped with an ABS system, a separate standard DOT 5.1 is issued. This composition cannot be combined with other liquids.
What kind of brake fluid should I put in my car?
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Rating: 4.0;
Votes: 1 What kind of brake fluid to pour into a car Alexey Krasnov: I will support Ivan in what he wrote about electrical conductivity in everything: the device shows electrical conductivity, some alcohols, for example, can conduct current, then, water itself is a dielectric and does not conduct current on its own, it conducts it what is dissolved in it.
Also, what’s wrong with water in brake fluid, as far as I know from physics - water does not compress at all under pressure, that is, if you pressed 1 cubic meter, then it was squeezed out by 1 cubic meter. In addition, the freezing point of water in any liquid directly depends on the proportions of water, for example in antifreeze this same water is 30-80%, the rest is isopropanol. I can’t say anything about boiling, and Denis didn’t conduct any tests. That is, the composition of these brake fluids and the boiling point are not known; many alcohols have a boiling point lower than that of water. Much more can be said, but you need to know at least the approximate composition of the liquids. I don’t want to say anything bad or good to the author, but this particular video is far from objective. Date: 2019-06-26
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Comments and reviews: 9
Nikolay Kiselev It’s just a little illiterately said, not the type of liquid after all - because DOT is a standard. That is, it was necessary to say a liquid of the DOT n standard (where n is 3, 4, 5, 5. 1, Also regarding water in the brake fluid - not only is freezing dangerous, it is also dangerous that the boiling point of the brake fluid at in the presence of water - it is greatly reduced and when braking when the pads get very hot - the pedal simply falls due to the formation of steam bubbles from the boiling liquid in the brake line, thereby the brakes lose their effectiveness, and it is necessary to point out that it is not recommended to use fluid that exceeds the standards without permission - it is not recommended, it changes both the composition and the additive package. Accordingly, all hoses, working and sealing elements must be protected from this type of fluid. The frequency of replacing brake fluid and its type should be checked with the car manufacturer; for many cars, even the replacement period varies greatly.
Alex04488 Denis, you also kept silent about the fact that old liquid not only boils, but also freezes. A couple of years ago there were severe frosts. so within a week about a dozen cars arrived with a problem that the clutch stopped working. The brake fluid in the system has frozen. the brakes are more loaded, and there is more fluid, as a result there is less moisture concentration. But in the clutch, the fluid accumulates moisture faster. (I have been monitoring this situation for many years. And the number of presses on the clutch pedal is several times higher than on the brake. With each press, air from the street enters the reservoir, naturally with moisture, so we find that the liquid accumulates moisture faster. and very I often see that the fluid in the brake system is still normal (more or less), but in the clutch the moisture concentration is off the charts.
Sergey Druzhinin They change the fluid because water has a lower density and compresses better than brake fluid. Over time, brake fluid absorbs water well and quickly wears out rubbing parts (even rubber seals. On motorcycles this is dangerous due to the uninformative, stepped (intermittent) front brake handle. If you press a little at first, braking does not occur. If you press harder, the handle (more precisely the master cylinder) overcomes some obstacle (cylinder wear belt) and the brake suddenly breaks into a stupor and the wheel (and the front wheel is even more dangerous) skids.
Andrey Voron The device may be good, but it doesn’t need to be measured in the tank. The brake fluid DOES NOT CIRCULATE. And old brake fluid circulates around the brake cylinders. AND NOTHING GETS INTO THE TANK. Therefore, you need to measure the drain a little from the brake cylinder. And from EVERYONE. And as you pump, the device will help you determine when you can stop pumping the current wheel. Then you can move on to the next wheel.
Alexey Good Denis, we both know that that piston from your video rusted from a crappy boot, and not from water in the brake. We also both know that in our experience it has never boiled under any braking. No condensation accumulates there. There are tightly tightened tubes throughout the entire system, and on the tank there is a lid with a rubber sealing ring. It’s just become fashionable to change everything and preferably more often.
Vladimir Shilov I was thinking about how we used to drive Soviet cars for years and years and decades and never changed the brakes, just topped them up and everything worked and didn’t freeze or boil or run. Mysticism It is clear that now the cars are not the same and the speeds are different. But the same mountains have always been there and sometimes on the descent the blocks emitted blue smoke. The pads were changed, but the brake fluid was not there. Something is wrong here.
Denis Kudryavtsev This device is not intended for checking brake fluid. I also fell for such a device and bought it. and started experimenting. First I added water to the brake fluid and the device showed the percentages correctly. But then I took distilled water. And the device began to work incorrectly. If there is only distilled water in the plug, then the device shows that everything is fine.
Alexander Starlikov Decided to change it last year, for prevention. VAZ14, 2012. bought Lukoil, the cuff between the vacuum and the cylinder was cut. I went to a friend for analysis, took the cylinder, set it up, shook it, drove it for a day and the same thing, well, in short, it happened twice. Then I went and bought a new cylinder and a more expensive brake, everything was fine, but I still cursed for a long time, draw a conclusion, gentlemen
Konstantin Orlenko Where is the normal brake fluid? Brembo, TRW, ATE? After all, these companies not only produce pads but also develop brake systems. As for DOT4, there are two types: class 4 and class 6, the difference is that class 6 freezes less in severe frosts and has better fluidity, which contributes to better performance of ABS, ESP, etc.
SINTEC Super DOT 4
Some of the most common and best brake fluids on the Russian market are SINTEC brand compounds. Despite the prevalence of lubricants from this company and a considerable range, the products are not suitable for foreign premium and luxury cars.
The price of DOT 4 SINTEC Super brake fluid is about 200 rubles per liter, which makes it the most affordable on the market. It is manufactured in the Moscow region and meets all quality standards.
The boiling point of the liquid is 240 degrees; after a year of active operation, this parameter decreases to 150 degrees. The viscosity of SINTEC Super DOT 4 remains unchanged for two years of use at low temperatures. Experts, answering the question of which DOT 4 brake fluid is better, often mention SINTEC, but they also note its disadvantage - a change in quality depending on the batch, and often for the worse.
Advantages:
- Affordable price.
- Maintains viscosity at different ambient temperatures.
- Compliance with class standards.
- High boiling point.
Flaws:
- Variation in quality depending on the batch.
Brake fluid ROS DOT 4
Domestic lubricating fluid that meets the requirements of class DOT 4. . Brake fluid boils at a temperature of 255 degrees, but after a year of operation it drops to 100 degrees. Viscosity remains unchanged when exposed to low temperatures.
The brand of brake fluid is quite widespread in both Russia and the CIS countries. Many car stores recommend ROS DOT 4 in response to questions from car owners about which DOT 4 brake fluids are better. The composition has good anti-corrosion properties, as noted by the manufacturer.
Advantages:
- Affordable price - 330 rubles per liter.
- High boiling point.
- Viscosity retention.
- Compliance with class standard.
Flaws:
- The need for frequent replacement due to a decrease in fluid quality after a year of active use.
DOT 4 Brake Fluid Requirements
In order for the TJ to fulfill its purpose, it must comply with certain parameters.
Boiling temperature
. No one needs to explain what boiling fluid in the brakes will lead to. Therefore, there is a certain threshold, below which the TJ is beyond the limits of permissible use. In the factory, that is, original, form, the lower limit: +250°C. However, brake fluid is hygroscopic, and over time it absorbs moisture from the air.
In this state it is called humidified, and the permissible temperature threshold drops to +165°C. Typically, this condition is observed in TJ 2 years after filling; a further decrease in resistance is already dangerous, which is why replacement is required.
The activity of hydrogen ions, in other words, the acidity of the liquid, denoted by pH. An acidic environment leads to corrosion, an alkaline environment leads to corrosion of any rubber that is nearby, primarily hoses and gaskets. The pH should be neutral, perhaps very slightly alkaline.
Viscosity-temperature characteristics are indicated on the bottle with TJ in mm2/s at -40°C. An extremely important thing in cold winter conditions, since viscosity increases at low temperatures. Upon reaching a certain limit, the liquid turns almost into plasticine, and it becomes impossible to push through it. For DOT 4 this figure is 1800, for class 6 (we also call it DOT 4+ or DOT 6) – 750°C. But the further north you go, the more you need to adhere to the first value. In general, except for the southern regions, you should not fall below 900°C.
Felix DOT 4
A high-temperature fluid that can be used not only in the brake system, but also in the clutch of modern cars. The composition includes a package of special additives that protect machine components from corrosion and reduce wear.
The boiling point is 230 degrees, the viscosity at -40 °C remains at 1800. Despite the fairly good characteristics, after a year of operation the liquid begins to lose them.
Advantages:
- Affordable price for brake fluid DOT 4 - 190 rubles per liter.
- Popularity and prevalence in the automotive market.
- Compliance.
Flaws:
- Decreased performance over a year of active use.
- In some cases, premature boiling was observed.
Brake Fluid Rating
Keep in mind that there is a lot of choice in the brake fluid market. And in large quantities there are products of frankly poor quality that do not stand up to any scrutiny. When you pour such liquid into your car, you may encounter a variety of problems.
Domestic products are usually of low quality, but even here there are very worthy manufacturers that can withstand competition with famous foreign brands. Therefore, we will consider various options that are of high quality and are recommended for use.
Castrol DOT 4
Brake fluid considered one of the best for cars operating in harsh weather conditions. The viscosity of the composition remains unchanged at a temperature of -40 °C. Boiling point - 265 degrees. Technical characteristics are maintained after a year of active use of the brake fluid; accordingly, replacement is carried out only after two years.
Advantages:
- Good viscosity at low temperatures.
- Maintaining a stable boiling point after two years of operation.
- Can be used in cars equipped with an ABS system.
- Meets class requirements and standards.
Flaws:
- High price.
- Small volume of produced containers.
Liqui Moly DOT 4
Popular and in demand brake fluid for cars. The boiling point of the lubricant is 230 degrees; after a year of active use, it drops to 155 degrees, in which the liquid is similar to domestically produced analogues. The viscosity of the liquid increases significantly at low temperatures, and therefore experts do not recommend using it in the northern regions of the country.
Advantages:
- Excellent corrosion resistance.
- Affordable price.
- High boiling point.
Flaws:
- Requires annual fluid replacement.
- Increasing the viscosity of the composition at negative ambient temperatures.
Bosch DOT 4
Brake fluids produced under the famous Bosch brand are notable for their low cost, which makes them stand out compared to other imported lubricants. The boiling point of the composition is within 230 degrees Celsius, but drops to 160 degrees after a year of active use. Throughout the entire service life, the viscosity remains unchanged. Maintaining viscosity at low ambient temperatures allows the brake fluid to be used in the northern regions of the country.
Advantages:
- Reasonable price.
- Good level of viscosity.
- Preservation of characteristics and properties during the first year of operation.
Flaws:
- Requires annual replacement.
Replacing brake fluid in a car
VAZ 2109 brake system diagram
The operational map of each car contains information about the frequency with which the manufacturer recommends replacing the brake fluid; most often it ranges from one to three years. However, depending on the intensity of use of the car, the replacement period may be calculated not by time, but by mileage.
Life time
Typically, the service life of high-quality fluid can reach 100,000 km. According to the recommendations of experienced vehicle service specialists, the average driver should change the fluid either every two years or after 60,000 km.
An important aspect that should be an important motivating factor for timely replacement is the saturation of the brake fluid with absorbed moisture, which contributes to the rapid failure of not only the working cylinders, but also the caliper pistons.
Again, due to oversaturation with moisture, the heat transfer capacity of the fluid changes, resulting in overheating of the brake system mechanisms and its failure. The consequence is the inability to fully control the car and an increase in its accident rate.
Complete replacement, not topping up
Among the myths wandering among “frugal” drivers, there is another one, that it is possible to add fluid, and not completely replace it. However, it is replacement that is an effective fight against watering of the liquid associated with its hygroscopicity.
Spent fluid, when mixed with new fluid that is added, does not at all help restore its properties to normal. Moreover, it is mixing that can cause corrosion in the system with subsequent destruction of its individual elements.
How to choose what to stop at?
It should be noted that the choice is quite simple, and it should be made on the basis of trust in the brands. Brake fluid is not that expensive, but safety is so expensive that you should try to save money here. But is it possible to mix different liquids, a question that does not have a completely unambiguous answer.
Some experts believe that if the basic components are identical, mixing is quite acceptable, but they focus on using products from the same company. However, you should always remember the notation:
1. Silicone base – silicone base.
2. LHM – mineral base.
3. Hidraulic – polyglycol base.
As a reason for replacing the brake fluid, not only its watering is recorded, but also repairs in general or in part of the brake system associated with the replacement of its components, as well as long-term idleness of the car without moving. It would be quite reasonable to replace the brake fluid in a car that was purchased not through a dealership, but on the secondary market.
The need for replacement can also be carried out using appropriate fluid monitoring equipment, which makes recommendations based on the boiling point and percentage of moisture content. The control unit is mounted in the expansion tank of the hydraulic system with a connection to the vehicle's electrical system.
The readings taken are compared with the minimum tolerances of current standards, the result of which is the decision to replace the fluid in the car’s brake system.
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What to consider when choosing brake fluid
The choice of brake fluid largely depends on the driving style: for an aggressive style, Castrol will be optimal, which, despite belonging to the DOT 4 class, has significantly better characteristics.
Domestic-made fluids are suitable for measured and quiet driving. When choosing, you need to pay attention to the viscosity: if the liquid will be used in the northern regions, then it is better to select more fluid compositions.
To preserve and maintain the performance of the brake system, it is better to choose Liquid Moly fluid - it protects the vehicle’s components and components from corrosion and increases their wear resistance.
Despite all the advantages of individual brands of brake fluid, it is advisable to purchase the one recommended by the car manufacturer and indicated in the vehicle’s technical data sheet. The manufacturer, as a rule, notes only the class of the liquid without any specifications, so the choice of a specific composition is made based on factors such as driving style, wear resistance and anti-corrosion, cost and preferences of the car owner.
What to consider when choosing a TZ
The main condition for partial replacement is consistency - once you have chosen brake fluid of a certain brand, you should not change it to another.
The manufacturer clearly describes the properties of the factory brake fluid poured into the system of a particular car. Also, recommendations are given on the choice of fluid for partial or complete replacement for the buyer-owner of the car for the most efficient and long-lasting operation of the brake system.
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What to choose
There are currently three types of brake fluids:
- mineral;
- glycolic;
- silicone.
Glycolic ones are the most hydroscopic, that is, they are more susceptible to the accumulation of water, which has a bad effect on the braking and lubricating properties of the brake fluid. But in other respects they are superior to their counterparts.
Silicone ones are often intended for cars of some foreign manufacturers. Most often, these are premium cars. Excellent performance, but, compared to others, lower lubricity.
Mineral brake fluids are considered obsolete and almost forgotten. Currently, they are extremely rarely used - more modern and technologically advanced analogues have appeared.
Each type of brake fluid has its own advantages and small disadvantages, which may not manifest themselves if they are changed within the time limits specified by the manufacturer.
It should be noted that the service life of the fluid differs from the recommended replacement periods specified by the car manufacturer.
You can’t get by with just periodic topping up of TK. Sooner or later it will need to be replaced. Photo: autoiwc.ru
