How to choose the best brake fluid for car?

Best Brake Fluids

A defective brake is the nightmare of every driver. In addition to brake discs and master cylinders, the brake fluid must also be checked regularly and in most cases replaced after two years at the latest.

From the older DOT 3 brake fluids to the latest DOT 5.1 and particularly temperature-resistant mixtures, we present the best brake fluids. Find out now in our comparison table which brake fluid passes the test by your demands.

When choosing a brake fluid for your vehicle, we recommend using a DOT 4, DOT 5.1 brake fluid for new cars.

Best brake fluid DOT 3, DOT 4, DOT 5.1

TOP 10 brake fluid DOT 3, DOT 4, DOT 5.1

Brake Fluids Buying Guide:

How to choose the right product from the above brake fluids test or comparison.

The most important facts in a nutshell:

1. Brake fluids are classified by DOT classes from DOT 3 to DOT 5.1. The higher the number, the newer and more powerful the fluid.
2. As a rule, brake fluid should be replaced every two years at the latest. You can use special brake fluid testers to check for yourself whether a change is necessary.
3. Brake fluids absorb water in their environment, e.g. from the brake hoses, over time as they heat up. When the moisture content of the brake fluid reaches 3.5%, a change is necessary.

If you want to buy the best brake fluid cheap, look for additives such as “Plus”, which stand for improved properties such as a higher boiling point.

Brake fluids transmit braking force from the brake pedal to the brakes in hydraulic brake systems. For the fluid to ensure a fast braking response, it must be reliable even at high temperatures and contain only a small amount of water.

Depending on the DOT class (“department of transportation”), it can take up to two years before the brake fluid needs to be replaced.

In our buyer’s guide, we present the performance and corrosion protection of the various DOT classes and show you when and how you need to replace the brake fluids.

Brake fluid tests show: Why should you pay attention to the right DOT class when buying?

Basically, before you buy brake fluid, you should check your vehicle’s owner’s manual to see which DOT class the brake fluid must match. In most passenger cars and motorcycles, DOT 4 class brake fluid is standard.

Cars that are fifteen years old or older still require DOT 3 brake fluid in most cases.

If the brake fluids on the market today, DOT 3 class fluids represent the oldest category and are surpassed in performance by the newer DOT 4 and DOT 5.1 classes.

This has concrete implications for you in terms of fluid durability and braking performance. DOT 3 brake fluids typically become unusable twice as fast as newer formulas. We recommend that you check the condition of your brake fluid once a year, especially on older cars, or have it checked at a repair shop.

The boiling points and viscosity or thickness of the DOT-3 brake fluid are responsible for the faster wear. When the brakes are applied and the brake system heats up, the brake fluid also gets hot.

The heat causes the brake fluid to become thinner. As a result, they can transmit braking force less effectively and you have to “pedal harder”.

DOT-4 brake fluid is the standard in most cars and motorcycles.

Since most vehicles require DOT-4 brake fluid, you have the widest range of manufacturers and fluids here. Unlike DOT-3 brake fluid, there is more choice in products here.

Basically, DOT-4 fluid outperforms its predecessor DOT 3 in durability and performance. On average, DOT-4 brake fluid needs to be changed every two years. This is because the fluid retains its viscosity even in high heat and can transmit brake pedal force.

When purchasing DOT-4 fluids, pay attention to the manufacturer’s specifications regarding boiling points. A DOT-4 fluid should not begin to thin below 155 °C. Some manufacturers, e.g. Motul and Bosch, supply their brake fluids with higher boiling points. This increases temperature resistance, especially at very hot outside temperatures of 35 °C and above.

With both DOT-3 and DOT-4 brake fluids, you must expect your brake system to wear out. Since the fluids absorb water when heated, complete corrosion protection of your brake master cylinder is not possible. To protect your brake system from rust, we recommend that you check your brake fluid regularly.

Tip: If your vehicle has an active safety system such as an Antilock Braking System (ABS), Traction Control System (TCS) or Electronic Stability Program (ESP), we recommend a brake fluid that exceeds the standard DOT 4 specifications, such as DOT 4 Plus. These work particularly reliably together with the electronic systems at very high or low temperatures.

Brake Fluid DOT 5

DOT 5 is a special class of brake fluid because it is based on silicone. This makes it unsuitable for use in current vehicles, but it is sometimes used in classic cars.

DOT 5.1 brake fluids form the latest and most powerful variant available

DOT 5.1 brake fluid is used especially in current sports cars from BMW, Porsche and Mercedes-Benz. To ensure that these brake very quickly and reliably at high speeds,

DOT 5.1 is the best alternative

In order for brake fluid to comply with the class DOT 5.1, its boiling point must be at least high.

DOT 5.1 brake fluid

Do the hydraulic fluid for car test yourself and see if DOT 5.1 fluid can be used in your car.

This means your brakes will work with DOT 5.1 brake fluid even in extreme outside temperatures. This also makes DOT 5.1. the best choice for electronic safety systems such as ESP.

DOT 5.1 brake fluid also offers the best corrosion protection because the fluid binds water more slowly. Nevertheless, we recommend that you check the fluid every two years and have it changed if necessary. The better preserved the brake fluid is, the less damage the brake system will suffer.

If your vehicle currently has a DOT-4 mixture, but according to the owner’s manual you can also use DOT 5.1, you do not have to completely dispose of your old DOT-4 brake fluid. In some cases, you can mix the fluids together. Here, look for a yellow sticker on the package that informs you about compatibility.

In the brake fluid comparison you will find the right category for your needs:

Are brake fluid boiling points reliable indicators of performance?

We give you an overview of the three criteria for brake fluids.

Dry and wet boiling points have an influence on performance and corrosion protection.

The dry boiling point is the temperature at which a new brake fluid boils, i.e. begins to lose its performance. This is 400 °F for DOT 3 brake fluids. DOT 5.1, on the other hand, only loses braking efficiency at 500 °F.

Due to heating and the environment such as brake hoses, the fluid absorbs water after some time. In this case, the wet boiling point of brake fluids is decisive, which is lower than the dry boiling point. The higher the wet boiling point, the better the performance of the brake fluid even after months of use.

We, therefore, recommend that frequent drivers, in particular, choose a DOT-4, DOT-4-Plus or DOT-5.1 brake fluid from Brembo, Castrol or Bosch, if possible.

Is brake fluid always changed by an auto repair shop?

Even if you have the brake fluid changed in the workshop, it is worth buying the fluid yourself

It is recommended to have the brake fluid changed in a workshop. The change requires not only a detailed knowledge of the brake system but also special tools such as an air compressor and collecting equipment.

In addition, special services such as the complete flushing of the brake system are in many cases already included as a service in the brake fluid change, so that even the last remnants of the old brake fluid are extracted and the brake system is freed from deposits. The professional disposal of the old brake fluid in hazardous waste is also usually included in the change.

We still recommend that you buy the brake fluid yourself, as the workshop often chooses a standard fluid here that is inferior in terms of performance to brand-name products, the DOT-4-Plus agent from Bosch.

How much does it cost to replace brake fluid?

The cost of draining, cleaning, filling, bleeding, testing is from 40 to 60 S, depending on the workshop. The price of disposal is usually included.

Advantages and disadvantages of the change in the workshop compared to independent change.

Advantages

• complete flushing of the brake system
• disposal of brake fluid included
• guaranteed functionality

Disadvantages

• fewer costs for brake fluid, if special tools are available

You can check the condition of the brake fluid yourself

The brake fluid reservoir in the engine compartment has markings that allow you to see if there is enough brake fluid. The color should be transparent to amber. If the fluid has turned brown and become cloudy, a change is urgently needed.

In addition, there are electronic brake fluid testers that give you an accurate indication of the moisture content in the brake fluid. However, we only recommend purchasing one if you intend to replace the brake fluid yourself anyway.

For the change, the old brake fluid must first be drained from all four wheels. Then the brakes are bled and filled with new brake fluid.

Frequently asked questions about brake fluids

How can you tell if the brake fluid needs to be changed?

You can hear problems with the brake fluid. If you hear grinding noises, and if the pedal bounces back and forth slightly when you depress the brake pedal, you should urgently check the condition of the brake fluid. Another critical sign is that the pressure point of the pedal decreases, i.e. the pedal is easier to push through.

Be careful when checking: if you notice that there is less brake fluid in the reservoir than intended, or your car’s LED indicator shows a lack of brake fluid, you should not simply add brake fluid. The level may indicate a leak in the brake system, which should be checked by a professional.

Is a DOT 4 or DOT 5.1 brake fluid the better choice?

Which product you should choose depends on which brake fluid your vehicle is designed for. For both passenger cars and motorcycles, only the brake fluid intended by the manufacturer may be filled.

There has not yet been a brake fluid test by Stiftung Warentest for brake fluids. A brake fluid test winner should have the highest possible wet and dry boiling point and be temperature resistant.