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Difference Between Dot3 and Dot4 Brake Fluid

car_jetta_pdDot3 vs Dot4 Brake Fluid

It is difficult to know how much we really know about the cars that we take for granted, once we have them on the road and running. There are many people that pay a lot of attention to the car’s detailing, and all it takes to make sure that the car shines like new all the time, however, how much effort do we pay in understanding the components and the small things that make this wonderful thing work, like the oil and break fluids? There are a few types of brake fluids that are normally used. One is called dot3, and another one is called dot4 brake fluid, but what are the differences between these two?

Brake fluid classifications

Dot3 brake fluid is considered to have the standard measurements required to take care of the normal braking system in a car. They have the capacity to handle heat up to certain stent due to its chemical components.

 Dot4 brake fluid works in the same manner as the dot3 fluid, however, it is a better fluid because it is capable of handling problems related to manufacture or improper usage of other brake fluids, thus becoming a more reliable component.


 Dot3 break fluid contains a mixture of polyalkyelen glycol and ether. They function very well in wet and heated conditions, as the brakes tend to heat up with constant usage, and that is the most important factor that the fluid needs to handle.

Dot4 break fluid contains borate, which is added to the glycol to make it more apt for the boiling point. The combination allows for the chemical stability of the fluid, even at very high temperatures, and water tolerance, which is very important for the proper functioning of the whole breaking system.


Dot3 brake fluid has a very good dry boiling capacity, and a very good wet boiling capacity as well. Once the fluid is exposed to the atmosphere and to water they act quickly, and very well.

Dot4 brake fluid acts better with a dry boiling capacity, however, they do not act so fast when it comes to the wet boiling capacity.

It is very important to understand the purpose of these components which may seem to be so insignificant, but that are however, extremely important for your car’s system. The brakes of your car are perhaps the most important thing that you need to keep in good working order, and understanding its functions is very important.


1. Dot3 fluid is the standard brake fluid approved for usage on every car.

2. Dot4 brake fluid is more complex, as it helps to maintain your braking system, as well while trying to handle any bad effects.

3. Dot3 is a glycol component which is good for boiling and heating resistance.

4. Dot4 contains borate to raise the boiling points of the fluid, and still handle corrosiveness.

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  1. very nice topic and thanks for the effort yet i want to ask if my car require only dot 3 and i live in hot country usually no rain so can i use the dot 4 or even i saw dot 5 which more complex and better for racing purpose so is it going to do any problem if i changed the type of the brake oil

  2. Dot 5 brake fluid is not appropriate for street cars. It’s application is intended for race cars. Dot 5, while more stable at high temperatures, will over time absorb more water into the system. This greatly affects the system’s ability as the absorbed water boils and creates gas pockets; a process which produces erratic and sometimes complete loss of brake function. Race teams through testing and applied knowledge determine their own schedules for regular flushing of brake systems using dot 5 brake fluid which is much more often than is necessary for street cars using dot 3 or dot 4 brake fluid.

    • Matt wrote:
      “Dot 5, while more stable at high temperatures, will over time absorb more water into the system.”
      No, DOT 5 is non-hygroscopic, which means it does not absorb water. Because moisture will not be absorbed, it tends to “pool” in the system, This is why a DOT 5 system needs to be flushed more often.


  4. Is it safe to mix Dot 3 and Dot 4? I heard it was but i’m not exactly sure.

  5. I have a Chrysler Pacifica – 2017 model. I was not sure if i can use a DOT 3 brake fluid, as i don’t know what type of brake fluid is already in the car. Can i go ahead a use the DOT 3 fluid, regardless of what ever is already there ?

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