Difference Between DOT 3 and DOT 4 Brake Fluid
The brake system is one of the things that needs to function properly in any emergency, so it is very important to take good care of it. Changing the brake fluid is part of the maintenance of your brake system and should be done every 1-2 years. Otherwise, rust can form in the brake system and damage other components.
There are two common types of brake fluid: silicone-based and glycol-based. Dot3 and Dot4 are popular glycol-based brake fluids that can be used in many vehicles. Dot3 is popular among general drivers, while Dot4 is more common in newer car models.
Difference between Dot 3 and Dot 4 brake fluid
The main difference between Dot 3 and Dot 4 brake fluid is the boiling point. Dot 4 brake fluid has both a higher wet and dry boiling point, making it better suited for higher performance. Both Dot 3 and Dot 4 brake fluids are glycol-based products used in braking systems. They are hygroscopic and will absorb moisture from the atmosphere, so care must be taken when storing and regularly changing potentially contaminated fluids.
Can Dot 3 and Dot 4 brake fluids be mixed?
Yes, you can mix Dot 3 and Dot 4 brake fluids. This means that since both brake fluids are glycol-based, they are compatible with each other. However, if your car is factory equipped with Dot 4, we do not recommend filling it with Dot 3, and vice versa.
If your car is factory equipped with Dot 3 and you know you will be towing a trailer or driving up steep hills a lot, we highly recommend refilling with Dot 4 instead.
Can Dot 5 be mixed with Dot 3 and Dot 4?
Dot5 is a silicone-based brake fluid.
- It does not absorb moisture from the air and is not compatible with ABS systems.
- It maintains its integrity and functions normally.
- It also has a higher boiling point than Dot3 and Dot4 brake fluids, making it suitable for overly aggressive driving.
However, it is not compatible with Dot3 or Dot4 fluids and should never be mixed. You should follow the manufacturer’s recommendations to see if your braking system is compatible with Dot5 brake fluid. What does boiling point mean? As mentioned above, Dot 3 and Dot 4 brake fluids are hygroscopic and will absorb moisture over time. This is why they should be changed every 1-2 years.
Brake fluid heats up quickly when braking frequently while driving up hills or towing a trailer. If it gets too hot and starts to boil, your car’s brakes will stop working. This is the last thing you want when you’re towing a trailer up a hill. Therefore, it is important that the boiling point is as high as possible.
The wet boiling point is measured when the brake fluid contains water, while the dry boiling point is measured when it does not contain water.
Dot3 vs Dot4: Which brake fluid is better?
Dot3 is the more popular of the two brake fluids, but Dot4 is quickly gaining popularity because it is compatible with standard traction control and anti-lock braking systems. Dot 4 has a higher boiling point, making it a good choice for all types of applications. It is often a little more expensive, but it is worth the purchase.
What happens if I use DOT 3 instead of DOT 4 brake fluid?
You can use DOT3 instead of DOT4 brake fluid, but it is not recommended. Both fluids are glycol-based, so switching will not cause damage to your brake system components.
However, DOT3 brake fluid has a lower boiling point than DOT4 brake fluid, which can be problematic in heavy-duty applications such as towing or driving on steep hills. As a general rule, you should always use brake fluid with the same specifications as the vehicle came from the factory.
What happens if you use the wrong DOT brake fluid?
This depends on the type of brake fluid you mix. With DOT3 and DOT4, nothing dramatic will happen other than a change in boiling point. DOT3 has a lower boiling point, so injecting DOT3 into a DOT4-based brake system may cause the brakes to deteriorate more quickly under heavy loads. This is not necessarily desirable if you drive downhill. Furthermore, both brake fluids are glycol-based and are not compatible with the newer DOT5 version, which is silicone-based.
How often should I change my DOT 4 brake fluid?
DOT4 brake fluid should be changed at least every two years. If you use your vehicle for heavy-duty applications, e.g. towing a trailer or frequently driving up and down steep mountain roads, and you use your tires a lot, it is ideal to change it even more frequently. This is because DOT4 brake fluid is hygroscopic and absorbs moisture from the air. Under heavy loads, this moisture evaporates into steam, creating air pockets and reducing braking performance.
How do I know which brake fluid to use?
You can always find information about which brake fluid is recommended for your specific vehicle in the owner’s manual. Or in some cases, this may also be displayed on the brake fluid reservoir cap, which you’ll find somewhere near the brake booster. In any event, you can’t go wrong by switching from DOT3 to DOT4 fluid, as this will increase its boiling point and make the brake system more durable under high loads. Doing the other way around, however, is not recommended.
Most modern cars use either a DOT3 or DOT4 brake fluid. In essence, these are similar fluids, as they both are glycol-based. The only difference is their boiling point, which is higher for DOT4.
As such, the DOT4 brake fluid is more suitable for demanding applications with a lot of heavy braking, such as when towing a trailer. Neither of them, though, should be mixed with the DOT5 brake fluid, as this one is silicon-based.
Due to a different chemical structure, these won’t mix well. Lastly, DOT3 and DOT4 brake fluids absorb moisture from the air, which affects their hydraulic properties. This is why they have to be replaced every two years.
