Good brake fluid ensures optimal braking system function. This must be replaced at the latest when the brake fluid tester indicates this. However, there are also intervals after which disposal of the old brake fluid is indicated and a sufficient quantity of one of the best brake fluids must be filled in to ensure its function. Please note that it is generally not a good idea to mix brake fluid. This applies in particular to different DOT brake fluids. Under no circumstances should DOT 5 brake fluid be mixed with DOT 3 brake fluid or DOT 4 brake fluid.
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Contents
The most important functions and properties of brake fluid
One of the most important properties of good brake fluids is their boiling point. Another important difference between brake fluids is their water absorption. In general, this absorption of water over time is one of the main reasons for changing the brake fluid every 2 years. The maximum permissible water content is only 3.5%. You can also have your brake fluid tested for this. Please note that some vehicles require the car's brake fluid to be replaced more frequently.
But what are the differences in brake fluids? These hydraulic working fluids can be divided into different classes. These are referred to as DOT 3, 4, 5, or 5.1. In principle, there are three important and quantifiable properties of brake fluids: the wet and dry boiling point and the viscosity/thickness.
What do good brake fluids cost?
As is so often the case, there is no direct connection between the product price and the actual performance of the product. Even in the area of the best brake fluids, there are sometimes differences of a factor of 15. We therefore urgently advise you to find out more about the different brands of brake fluid with the help of our test. However, this cannot replace detailed advice, but it can still be a first point of reference. Please also consider that brake fluid is often very toxic, so the brake fluid must always be disposed of professionally and as hazardous waste. For all work, you must therefore collect the old working liquid in suitable, sufficiently large and securely closable containers. Under no circumstances should you use food containers or containers shaped like food to avoid dangerous mix-ups.
More important notes
If you notice when examining the brake fluid (e.g. by visually inspecting the brake fluid in the expansion tank) that it has become cloudy or dark, you should examine it more closely. The color of the brake fluid is usually clear or golden yellow. In the course of time, however, it can happen that this becomes increasingly cloudy or even green/red. However, if your brake fluid is already black, you should stop driving your vehicle as your brakes can fail completely at any time.
If brake fluid gets on your paint, it will cause permanent damage. Some hobby mechanics even swear by brake fluid when it comes to removing paint from plastic parts. Please note, however, that this can also damage the plastic surface. Always be very careful when handling brake fluid.
Also read: Motor oil test: these are the best motor oils!
The best Manufacturer of brake fluid
When it is time to change the brake fluid, this is indicated in part by a brake fluid indicator on the dashboard. The change is usually necessary every two years from DOT-4, with DOT-3 this can be necessary after one year. A timely change also ensures that there is less water in the system, which slows down the corrosion of the brake system components.
ATE
The ATE brake fluid is wide-ranging and covers all brake fluid requirements. It doesn't matter whether you are looking for such a working fluid for a classic car or a modern vehicle with ABS and ESP. The experience of this manufacturer has a positive effect on the high quality of all products.
BOSCH
This Bosch brand produces very good brake fluids, and you can even buy them for a comparatively low price. This makes them worlds cheaper than the most expensive products on the market. When ordering a specific product, however, always make sure that it is also approved for your vehicle. In addition, as already written, the most important objective parameters are dry and wet boiling points and viscosity.
CASTROL
This brand manufacturer offers a whole range of different working fluids for your vehicle. The motor oils of the brand are certainly best known. But Castrol's brake fluids are also among the best available on the market.
FERODO
In addition to brake fluid Ferodo itself, this company also offers a device for determining the boiling point. This gives an indication of how much water has already penetrated. If the boiling point continues to fall, gas bubbles may form when the brake system heats up. These prevent you from being able to brake and must therefore be avoided.
Brembo
Brembo brake fluids offer a much higher boiling temperature (both wet and dry boiling) which is well above the minimum values for the relevant category. This not only makes your brake system more resistant to possible vapor locks, but the premium brake fluids also offer better performance at low ambient temperatures.
LIQUI MOLY
This company is also known in particular for the motor oils it sells. But the brake fluids offered are also ideal for use in passenger cars. These not only work in drum and disc brake systems, but some vehicle manufacturers also use them in clutches.
Motul
If you are looking for a brake fluid manufacturer whose products will prepare you for all eventualities, you should choose Motul. This company offers everything from brake fluids for classic cars to classic brake fluids and products for racing.
Conclusion
Today, DOT 4 brake fluid is the standard for classic cars and motorcycles. The older DOT 3 brake fluid is only used in some older vehicles (built before 2005). Under certain circumstances, however, it may also be permitted for these models to switch to DOT-4 under certain conditions. It is best to ask your specialist workshop about this. The silicone-based DOT-5 fluid is mainly found in classic cars, while DOT-5.1 is used in sports cars in particular. When changing the brake fluid in a specialist workshop, make sure that a good brake fluid for your vehicle is poured in there.
A tip from CarTipsandmore: DOT-5 brake fluid has a silicone base, therefore Mixing with other brake fluids is prohibited. In theory, you can mix DOT-3 brake fluids with DOT-4 brake fluids because both are glycol based. However, this is not permissible because it not only changes the boiling point. Additionally, be aware that even the best DOT-4 brake fluid is significantly more aggressive than its DOT-3 equivalent. Therefore, in the case of a complete replacement, you must ensure that the seals and other components are also suitable for the DOT 4 variant.
