Brake fluid dot-4. Which is better?
Composition and characteristics of brake fluid DOT-4
DOT-4 brake fluid is 98% polyglycols. The remaining 2% are additives.
It is important to understand that there is a standard that regulates the composition of brake fluids. This standard is created and maintained by the US Department of Transportation. And any liquid, regardless of the manufacturer, in theory must comply with the characteristics prescribed in the standard, if it belongs to the DOT family. In practice, this is almost always the case, at least for well-known brands.
There are several regulated characteristics. First, it's the base. The DOT-4 brake fluid base consists of complex alcohols, the so-called polyglycols. These alcohols have good lubricity, are absolutely incompressible, remain functional down to –42°C on average, and boil at a temperature not lower than +230°C. Also, all alcohols of the glycol group are characterized by hygroscopicity - the ability to absorb water from the environment and dissolve water in its volume without sediment.
Secondly, it is a package of additives. Additives improve the performance properties of the fluid. The composition of additives is also regulated. And both in qualitative and quantitative terms.
This means that if you purchase brake fluid labeled DOT-4, then it is guaranteed to contain the minimum set of those components that ensure its operation within the limits indicated by the standard.
However, the regulation allows the addition of third-party components or an increase in the proportion (not a decrease), which may change some of the characteristics of the brake fluid. Usually for the better. For example, they reduce the low-temperature viscosity, increase the boiling point, or make the liquid less susceptible to the process of absorbing moisture from the atmosphere.
Manufacturers at a Glance
The modern market is replete with offers of DOT-4 class brake fluid. Let's take a look at a few well-known products in ascending order of cost, starting with the cheapest.
- Dzerzhinsky DOT-4. It costs about 220-250 rubles per liter. Does not boil up to +260°C. It tolerates negative temperatures well, at least fits into the standard. However, it does not contain in its composition additional components that resist the absorption of water from the environment. Requires mandatory replacement after 2 years, regardless of the intensity of use of the car. Perfect for classic VAZ models, outdated foreign cars or other cars with drum brakes. It can also be used in newer cars, but it is important to follow the replacement schedule.
- Syntec Super DOT4. Another cheap option. The cost is about 300 rubles per 1 liter. Will not boil up to +260°C, will not freeze down to -40°C. It is also desirable to update this fluid in the system completely after 2 years of use. It showed itself well in relatively old VAZs, such as Granta and Priora.
- TRW Brake Fluid DOT Fluid from a well-known manufacturer of expensive and high-quality suspension and braking system elements. The cost is in the range of 400-500 rubles per 1 liter. Has positive reviews online from car owners.
- Bosch DOT4. The manufacturer does not need advertising. The price for 1 liter is about 500 rubles. Despite the relatively low declared characteristics (the boiling point is only + 230 ° C, that is, at the minimum allowable level), it is distinguished by its stable quality. Motorists note that even after 3 years of operation, when checking the fluid for water content, the tester does not always write it off as completely unusable, but only recommends a replacement.
- Pentosin Super DOT 4 plus. Liquid with enhanced low- and high-temperature characteristics. Suitable for use in foreign cars with disc brakes. In a "dry" state, it will not boil until it reaches +260°C.
- Tosol-Sintez FELIX DOT4. Domestic product from the middle price segment. It has proven itself both in domestic cars and in foreign cars. It is successfully used in the brake systems of Japanese cars, such as Mitsubishi Lancer 9 and Honda Accord 7. According to the results of independent tests, FELIX DOT4 fluid fully confirmed the characteristics declared by the manufacturer.
- Castrol Brake Fluid DOT Liquid with high low temperature fluidity and good boiling resistance. It costs an average of 600-700 rubles per liter. The brand in this case speaks eloquently for itself. It has mostly only positive reviews online.
- VAG DOT 4. Branded fluid for cars of the VAG concern. In addition to the price (about 800 rubles per 1 liter), it has no drawbacks.
When choosing a brake fluid, you should be guided by several rules. Firstly, do not buy liquids of incomprehensible brands, especially those that are clearly cheaper than even the minimum price tag for a product from more or less reputable manufacturers. Second, try to find out which fluid the automaker recommends. Often this is just a publicity stunt. However, if a particular fluid is recommended by the car manufacturer, then it will be 100% compatible with your brake system.
And most importantly: do not forget to change the brake fluid no later than 3 years of operation. Even expensive options after 3 years will accumulate a dangerous amount of water in their volume, which can lead to sudden boiling of fluid in the system and complete or partial failure of the brakes.
