The Difference Between Dot 3 and Dot 4 Brake Fluid

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The Difference Between Dot 3 and Dot 4 Brake Fluid

When considering what is the difference between dot 3 and dot 4 brake fluid, you will find that each type is capable of handling a variety of conditions and road types.

The Difference Between Dot 3 and Dot 4 Brake Fluid

DOT 3 is probably the most popular form used in automobiles and trucks today, as it provides excellent braking power. DOT 4, though, is also gaining popularity because of its use in high-performance racing vehicles. The real difference in brake fluid isn’t just in the fluid’s viscosity level – there are many other factors that determine how well the system works. Let’s take a look at what they are.

Boiling Point

The real difference in brake fluid lies in the boiling point of the product. Just as oil has a different boiling point than water, so do different auto parts have different thresholds for operating at their best.

DOT 4 Boiling Point

There are a number of reasons why the boiling point of DOT 4 brake fluid may vary. It may depend on the type of material the part is made out of, its construction, and the ambient temperature. The amount of heat the fluid undergoes to reach its boiling point can be affected by many factors, including the type of fuel it’s using, the quality of manufacturing, and even the type of lubrication used.

DOT 3 Boiling Point

The real difference in DOT 4 brake fluid is found when comparing its boiling points with those of standard automotive oil.

Oil naturally has higher boiling points than water, as it is a petroleum-based product. However, water has been shown to have a higher tolerance to high temperatures, as well as an ability to self-regulate its boiling point, meaning it doesn’t go beyond a certain temperature before becoming useless. This means that while both types of oils will work for a given make or model, they differ in how they react when temperatures get too high.

As stated above, DOT 4 brake fluid is made of thicker components that allow it to resist hydrostatic pressure, which occurs when oil boils from a hot engine. This means that the boiling point is not going to drop below the typical range, which means that a small amount of hydrostatic pressure can build.

However, this does not mean that a car needs to run the risk of hydrostatic shock, which is a potential fatal accident. If there is not enough hydrostatic pressure, the difference in temperature between the hot engine and the normal operating temperature is enough to cause the fluid to boil, and this will cause problems.

Brake Fluid Grades

Also, there are several different grades of brake fluid, and you want to be sure that you choose the right one for your specific application. You will also want to know what safety measures need to be taken before and after you apply the proper amount. These should always be discussed with an auto mechanic or dealer so that you will know what you should be looking for when you purchase brake fluid.

Problems of Low-Quality Brake Fluid

Brake Fade

A comparison of DOT 4 and standard automotive oil shows that one of the biggest factors contributing to brake fade is uneven wear. As the braking pads work to slow or stop the car, friction between the pads slows the fluid down and causes it to boil. Because this is the case, it’s important for brake pads to always be clean and free of any debris.

Cleaning your brakes often helps, but it’s also important to have them as clean and free of buildup as possible. Otherwise, brake fluid is likely to run dry, causing brake fade, more than if it were still being used.

Decreased Cooling Level

Another factor contributing to brake fade is a decreased level of cooling. Since brakes are heated, they draw more heat from the engine, and the rest of the system, including the engine cools itself by drawing power from the battery. As more heat is drawn than needed, cooled brakes begin to run dry.

The problem with using low-grade auto fluids is that they don’t provide the adequate cooling effect needed to prevent brake fade. The higher the quality of fluid you use, the better the cooling effect will be, as well as longer brake life.

This feature is designed to keep the temperature constant and prevent the fluid from expanding and contracting when the temperature is out of control. If the temperature of the fluid reaches or exceeds the freezing point, the fluid will lose its viscosity and become a liquid. There are also high-temperature DOT 4 fluids available for high performance automobiles that are appropriate for all types of cars and driving situations.


So, what makes a difference between the DOT 3 and DOT 4? Well, you will want to find one that is specifically designed for your particular brand of vehicle. Not all manufacturers make the same quality product, so it is important that you get the right one.

It is important to always buy the correct type of fluid for your specific application, as well as one that will prevent problems in case they do occur. A DOT 4 brake fluid can be used for cars with standard drums, but it is usually only recommended for those vehicles with the -3 compression option.

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