The topic of brake fluid isn’t well-understood. The brake fluids are in charge of transferring braking pressure from the lever to the brake pads. These fluids must be non-compressible to transfer force properly.
Some individuals are unaware that brake fluid has various ratings, which might impact how well their car works.
Key Takeaways
- DOT 4 brake fluid exhibits a higher boiling point than DOT 3, providing better resistance to thermal breakdown.
- DOT 4 fluid absorbs moisture more slowly, reducing the risk of corrosion in the braking system.
- Although both fluids are glycol-based, DOT 4 offers improved performance under demanding conditions and is compatible with DOT 3 systems.
Dot 3 Brake Fluid vs Dot 4 Brake Fluid
The difference between Dot 3 Brake Fluid and Dot 4 Brake Fluid is that DOT 3 brake fluid is non-silicone, petroleum/non-mineral based, completely synthetic brake fluids that may be used in a variety of clutch and braking applications, whereas DOT 4 braking fluids are glycol ether-based, with the addition of borate esters to increase performance.
DOT 3 brake fluid is a glycol-based braking fluid that is used in the majority of modern cars. Continue reading to learn more about this braking fluid’s applications and limitations.
The brake fluid provides the force required to stop the car, whether you have drum brakes or disc brakes.
DOT 4 is a glycol-ether-based braking fluid that also includes borate ester (boron-containing oxyanions), which increases the boiling point of DOT 4.
All of this adds up to DOT 4 brake fluids being an excellent performance brake fluid with better dependability. DOT 4 is used as an interchangeable brake fluid instead of DOT 3.
Comparison Table
| Parameters of Comparison | Dot 3 Brake Fluid | Dot 4 Brake Fluid Brake |
|---|---|---|
| Definition | DOT 3 brake fluids are non-silicone, petroleum/non-mineral based, completely synthetic brake fluids that may be used in a variety of clutch and braking applications. | DOT 4 braking fluids are glycol ether-based, with the addition of borate esters to increase performance |
| Wet boiling point | 400°F/205°C | 445°F/230°C |
| Dry boiling point | 285°F/140°C | 310°F/155°C |
| Composition | Glycol Ether | Glycol Ether/Borate Ester |
| Popularity | Dot 3 Brake Fluid is the more popular of the two brake fluids | Because it works with normal traction control and anti-lock braking systems, Dot 4 Brake Fluid is fast gaining popularity |
What is Dot 3 Brake Fluid?
DOT 3 brake fluids are non-silicone, petroleum/non-mineral based, completely synthetic brake fluids that may be used in a variety of clutch and braking applications. It’s created by combining glycerin with alcohol.
The braking fluid is based on polyethene glycol ether technology for excellent performance.
The major benefit of DOT 3 brake fluid is its high boiling points, ensuring safe and reliable braking performance at high pressures. This braking fluid is intended to resist both high and low temperatures without boiling or thickening.
DOT 3 brake fluids may tolerate high temperatures of up to 250° C.
This brake fluid may be used to top up or re-fill clutch and brake systems in heavy-duty trucks, motorbikes, 4WDs, and passenger automobiles. It’s also suitable for agricultural, construction, and mining machinery.
In DOT 3 brake fluid, the rubber component swell is low, resulting in less fluid loss and leakage. It also offers high corrosion resistance, extending the life and dependability of the brake system’s components.
It is a popular brake fluid that has been used in domestic cars’ braking systems for a long time. DOT 3 braking fluids are glycol-ether-based and include a combination of poly-alkylene glycol and ether.
DOT 3 absorbs moisture from the environment in most situations.
What is Dot 4 Brake Fluid?
DOT 4 braking fluids are glycol ether-based, with the addition of borate esters to boost performance. The wet and dry boiling points are two things that the borate esters enhance.
In comparison to DOT 3, DOT 4 brake fluid has a higher and more stable boiling point. However, when it starts to absorb water, the boiling point drops faster than DOT 3 brake fluid.
According to the established criteria, DOT 4 should have a minimum wet boiling point of 155°C and a minimum dry boiling point of 230°. Only use the DOT 4 braking system if your brake system requires it or if the automobile manufacturer has stated it.
This brake fluid is not recommended for use in lower or higher-grade cars.
As the braking fluids continue to absorb water from the air, their boiling point will drop. If you don’t change your braking fluid regularly, the rubber portions in your wheel cylinders and master cylinder will corrode.
It is suggested that the DOT 4 braking system be replaced every two years to ensure the brake system’s optimal safety and functionality. When water contaminates the braking system, its lifespan is reduced.
This braking fluid is capable of withstanding temperatures of up to 311 degrees Fahrenheit. At 40 degrees Fahrenheit, DOT 4 has a viscosity of 1800.
Main Differences between Dot 3 Brake Fluid and Dot 4 Brake Fluid
- DOT 3 brake fluids are non-silicone, petroleum/non-mineral based, completely synthetic brake fluids that may be used in a variety of clutch and braking applications, whereas DOT 4 braking fluids are glycol ether-based, with the addition of borate esters to increase performance.
- The wet boiling point of Dot 3 Brake fluid is 400°F/205°C while the wet boiling point of Dot 4 Brake fluid is 445°F/230°C.
- Dot 3 Brake Fluid is composed of Glycol Ether, whereas Dot 4 Brake Fluid is composed of Glycol Ether/Borate Ester.
- The dry boiling point of Dot 3 Brake fluid is 285°F/140°C whereas the dry boiling point of Dot 4 Brake fluid is 310°F/155°C.
- While Dot 3 Brake Fluid is the more well-known of the two brake fluids, Dot 4 Brake Fluid is quickly gaining popularity due to its compatibility with standard traction control and anti-lock braking systems.
Last Updated : 11 June, 2023
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.
I appreciate the detailed explanation and the comparison between DOT 3 and DOT 4 brake fluids. It helped me understand their differences better.
The article effectively highlights the benefits and limitations of both DOT 3 and DOT 4 brake fluids, making it easy for readers to comprehend.
The humorous tone in describing the consequences of not replacing the DOT 4 braking system every two years brings a lighthearted touch to an otherwise technical topic.
I found the comparison table very useful, especially for those looking for a quick reference to the disparities between DOT 3 and DOT 4 brake fluids.
The post clearly outlines the importance of using the right type of brake fluid for different vehicles and the potential consequences of not doing so.
I disagree with the comparison of DOT 3 and DOT 4 brake fluids. The differences in their performance under different temperatures could have been explored in more detail.
The thorough explanation of the composition and boiling points of DOT 3 and DOT 4 brake fluids is very insightful. It’s crucial for vehicle owners to understand these differences.
This article provides valuable information for car owners who want to ensure the proper maintenance of their braking systems. Well done!