Difference Between Dot 3 and Dot 4 Brake Fluids | Dot3 vs Dot4

Brake fluid plays an important role in the brake system of a vehicle, it produces pressure in the brake system when we press the brake pedal and this pressure helps the rotors to press the brake pads and stop the vehicle.

So, several categories of brake fluid are present in the market, and the common thing between these categories is that they all follow the specifications set by the government.

People use Dot 3 and Dot 4 brake fluid most commonly but maximum time they confused about that does it matter if they replace dot4 brake fluid with dot 3, so the answer is “Yes” but also we need to consider few factors and first analyse what is the difference between these 2 categories of brake fluids, to answer this question we are up with this article.

Boiling Point  

Before looking at their boiling points, first understand that there are two types of boiling points: first is the dry boiling point which indicates the boiling point of the fluid from the new container and the second is a wet boiling point which indicates the boiling point of the fluid which is in the working condition. 

So when brake fluid is under high pressure it tends to boil and therefore the boiling point is an important factor to differentiate between dot3 vs dot4 brake fluids.

Dot 3

The dry boiling point of dot 3 brake fluids is 205-degree Celsius and the wet boiling point of the dot 3 fluids is 140-degree celsius, which is less than dot 4 brake fluids, which means these type of brake fluid evaporate more quickly and therefore we should use these types of brake fluid in standard vehicles which do not use brakes system hardly, one should not use these brake fluids in racing cars and other heavy working vehicles, as with heavy braking the brake fluid will boil more easily producing vapors and can produce complications in the vehicle.

So if you do not use the brakes of your vehicle aggressively then you should go for these types of brake fluids.

Dot 4

The dry boiling point of the dot 4 brake fluids is 230-degree Celsius and the wet boiling point is 155-degree Celsius, now on comparing from above you can observe that it is more than the dot 3 brake fluids and hence these types of brake fluids can withstand more pressure and will take more time to evaporate, therefore the police vehicles and also the racers use this type of brake fluids because they have to use brakes aggressively which in turn will exhibit more pressure on the brake fluid.

Boiling Capacity

The wet boiling capacity of a fluid tells us about how well it can function in the presence of water and the dry boiling capacity tells how well it can work in the open air, therefore the boiling capacity of the brake fluids are also taken into consideration when comparing them, this property is also interrelating to the boiling point.

Dot 3

The Dot 3 brake fluids have both wet and dry boiling capacities which means they can perform well in both dry and wet conditions.

Dot 4

The dry boiling capacity of the dot 4 brake fluids is excellent which makes them work best in the dry condition but on the other hand, their wet boiling capacity is not so good in comparison to dot 3 brake fluids, therefore these fluids are not ideal for use in the wet conditions.

Chemical Properties

These two categories of brake fluids also vary in their chemical compositions.

Like any other brake fluid they have three components

Solvent– It is 60-85 percent of the brake fluid

Lubricant– It is 5-35 percent of the brake fluid

Additives– It is 2-5 percent of the brake fluid

Dot 3

The dot 3 brake fluids are glycol-based, these are a mixture of polyalkylene glycol, ether, and other additives, most of the vehicles running on the road use this fluid, the glycol part of this fluid makes it hygroscopic and gives it an affinity to water.

The structure of dot 3 brake fluid gives it the ability to work in the extreme wet and dry condition therefore its both wet and dry boiling capacities are high.

Dot 4

The dot 4 brake fluids are a blend of glycol and borate.

The structure and components of these types of brake fluids make them withstand high-temperature conditions and also make them stable than other fluids, these brake fluids best suit when we are using our vehicle at high altitude.

Cost

Yes, how can we forget about the cost? It is also one of the distinguishing factors between these two competitors.

Dot 3

Dot 3 brake fluids are much cheaper than dot 4 brake fluids, the prices of these brake fluids are very reasonable.

Dot 4

The dot 4 brake fluids are more expensive than any other types of fluids, it costs approx three times more than the dot 3 brake fluids, but its excellent properties make it worth the money

Frequently Asked Questions

Q1: What are the causes of the low brake fluid?

Brakes of your vehicle will stop working properly when the brake fluid is low in the brake system, as the fluid will not be able to produce as much pressure to stop the vehicle through the brake, there can be various causes of low brake fluid.

  • Leakage in the brake system of the vehicle is the most common reason for the low brake fluid, leaking of the brake fluid can be because of the worn-out parts of the brake system.
  • Even a little damage in the brake line of the brakes can cause low brake fluid.
  • Because of the worn-out brake pads, the brake piston has to travel more distance and thus will require more brake fluid which will cause low brake fluid.    

Q2: What are the signs that tell that one should change the brake fluid?

So many of the time when the brake of your vehicle starts acting weird, you do not know what to do exactly to resolve the issue, most of the time the cause of this weirdness is the bad brake fluid in the brake system. You need to change this fluid with time and you will get to know when you have to change the fluid by looking at these signs.

  • The anti-lock braking system light most commonly known as ABS light will start illuminating when the brake fluid needs a replacement.
  • The brake pads of your vehicle will not work properly indicating to change the fluid.
  • The burning smell after every time you press brakes also indicates bad brake fluid, in such conditions you should immediately take the action otherwise it can also cause damage to the brakes of your vehicle.
  • You will face problems in pressing the brake pedals or it will take your energy more than usual to press the brakes.
  • Weird types of noises will come while using the brakes.

You should change the brake fluid in approximately 2 years, to keep your vehicle running softly.

Q3: What will happen if I use the wrong brake fluid?

Most of the time people mix two brake fluids or use incorrect brake fluid and do not realize that they are damaging their vehicle unknowingly, so you should always use a brake fluid according to the requirement of your vehicle.

Here you can see how using a wrong brake fluid can affect your vehicle

  • Wrong brake fluid can overheat the vehicle when we use the brakes frequently.
  • Wrong brake fluid will also give bad lubrication.
  • It will damage the transmission of the vehicle

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