Your vehicle’s brake system relies on specialized fluids to function safely and smoothly. Two common ones are brake fluid and hydraulic fluid. Although they may seem similar, they serve different purposes and have distinct features. Brake fluid is designed to handle the high heat and pressure in your car’s brakes, while hydraulic fluid is used in many other machines, like excavators or garbage trucks, to move power through their systems.
Knowing the difference helps you choose the correct fluid and keep your brakes working their best. At Fubex Lubricants, we provide premium-quality brake fluid and hydraulic fluid for all types of vehicles and machinery. Enjoy fast shipping, a price match guarantee, and hassle-free returns. Need help choosing the correct fluid? Call us at +971 50 544 9614 — our friendly team is ready to assist you!
The Importance of Brake System Fluids: Brake Fluid vs. Hydraulic Fluid
Understanding the distinction between brake fluid and hydraulic fluid is essential for ensuring the safety and effectiveness of your brakes. Let’s examine what brake fluid does and why it’s necessary for your vehicle.
What is Brake Fluid?
Brake fluid is a special liquid made for your car’s brake system. It helps your brakes work properly by doing three main jobs:
- Transfer Force: When you press the brake pedal, the brake fluid transfers pressure from the pedal to the brake pads or shoes. This causes them to press against the rotors or drums, slowing down or stopping your car.
- Lubricates Parts: It keeps the moving parts inside your brake system smooth and protects them from rust or wear.
- Handles Heat: Braking generates a significant amount of heat. Brake fluid has a high boiling point, so it doesn’t easily overheat. This helps prevent brake fade and keeps your brakes strong even when they get hot.
Brake fluid is usually glycol-based (DOT 3, DOT 4) or silicone-based (DOT 5). Always use the type your vehicle’s manufacturer recommends for the best performance and safety.
Understanding Brake Fluid
What is Brake Fluid, And Why Is It Important?
Brake fluid is a special type of hydraulic fluid used in your vehicle’s brake system. It helps transfer the force from your foot on the brake pedal to the brakes at the wheels, making your car slow down or stop.
Brake fluid does not compress. When you press the brake pedal, the fluid moves through the brake lines, pushing the brake parts until the brake pads come into contact with the wheels. This is how your car comes to a safe stop.
Because brake fluid is so important, anything that lowers its quality—like moisture from the air—can make your brakes weaker and less safe.
What are the Main Types Of Brake Fluid?
The two common types are DOT 4 and DOT 5.
- DOT 4 is glycol-based.
- DOT 5 is silicone-based. It does not absorb water and can withstand higher pressure before boiling into a gas.
A higher DOT number means a higher boiling point, which is essential. Brake fluid works best as a liquid, not a gas, because gas can compress under pressure and reduce braking power.
If you drive in challenging conditions or frequently use your brakes, a higher boiling point fluid, such as DOT 5, is often recommended.
Types of Brake Fluid – DOT 3, DOT 4, DOT 5, and DOT 5.1
Let’s examine the primary types of brake fluid and what distinguishes each one.
DOT 3
- Base: Glycol-based
- Dry Boiling Point: 205 °C
- Wet Boiling Point: 140 °C
DOT 3 has the lowest boiling point of all brake fluids. It absorbs water easily (called hygroscopic), so it needs to be changed every few years to stay effective.
DOT 4
- Base: Glycol-based with borate ester
- Dry Boiling Point: 230 °C
- Wet Boiling Point: 155 °C
DOT 4 has a higher boiling point than DOT 3 and is used in most cars made after 2006. It costs more than DOT 3 because it contains additional chemicals. DOT 4 is very common in Europe and the USA.
DOT 5
- Base: Silicone-based
- Dry Boiling Point: 260 °C
- Wet Boiling Point: 180 °C
DOT 5 does not mix with water or other brake fluids. You must thoroughly flush the system before using it. It has a stable thickness (viscosity) at many temperatures, does not damage paint, and has a higher boiling point. However, DOT 5 is not compatible with ABS (anti-lock braking systems).
DOT 5.1
- Base: Glycol-based
- Dry Boiling Point: 270 °C
- Wet Boiling Point: 190 °C
DOT 5.1 is an upgraded version of DOT 4, featuring additional chemicals and a significantly higher boiling point. It is often referred to as racing brake fluid because it can withstand higher temperatures.
How to Know If Your Brake Fluid Needs Changing
Watch out for these signs that your brake fluid may need to be replaced:
Light Turns On
If the ABS warning light comes on, it may indicate that your brake fluid is low or needs to be changed. Sometimes, the light may turn on for other reasons, but this is one of the first things to check.
Changes in Brake Pedal Feel
Does your brake pedal feel soft, spongy, or loose when you press it? This often means your brake fluid is low or old and may need to be replaced.
Burning Smell or Strange Sounds
A strong, burning smell after heavy braking—such as when going downhill—can indicate that your brake fluid is overheated or burned. If you also hear squealing, squeaking, or screeching noises, it’s time to check your brakes and fluid.
Poor Braking Performance
Your brakes should feel quick and responsive. If they feel weak or take longer to stop, your brake fluid might be low, dirty, or worn out. Worn brake pads or other brake parts can also cause it.
Differences Between Brake Fluid and Hydraulic Fluid
Composition
Brake fluid is made especially for car brake systems. It adheres to strict safety and performance standards to ensure your brakes function properly. Hydraulic fluids, on the other hand, can be manufactured in various ways, depending on their intended use, such as in machinery or other hydraulic systems.
Boiling Point
Brake fluid has a higher boiling point than most hydraulic fluids. This is important because braking generates a significant amount of heat. Using a hydraulic fluid with a lower boiling point in your brakes can cause brake fade and reduce the effectiveness of your brakes.
Compatibility
Brake fluid is specifically designed to work with the rubber seals and other components in a brake system. Using the wrong hydraulic fluid can damage these seals and parts, potentially leading to brake failure.
Although both brake fluid and hydraulic fluid work in hydraulic systems, they are not the same. Brake fluid is made to provide pressure, lubrication, and temperature control in your brakes. Always use the type of brake fluid recommended by your car’s manufacturer and follow the maintenance schedule to keep your brakes safe and strong.
Also Read: Why It’s Important to Change Your CVT Fluid and When to Do It?
What is Hydraulic Fluid?
Hydraulic fluid is a liquid that helps transfer energy in hydraulic systems, like those used in hydraulic brakes, excavators, and garbage trucks. Its main job is to move power through the system, but it also seals parts, reduces friction, and helps clean out small particles.
When choosing a hydraulic fluid, one crucial factor is its viscosity (the thickness or thinness of the fluid). The fluid must work well even at the highest temperatures the system will reach. Another issue is foaming, which can lower performance. Any foam in the fluid should be removed to keep the system running smoothly.
What is Hydraulic Oil?
Hydraulic oil is a type of hydraulic fluid composed of base oil and specialized additives. It transfers energy, cools, and lubricates hydraulic systems. It also helps reduce corrosion and works well in a wide range of temperatures.
However, hydraulic oil is flammable, which means it can catch fire under high pressure if sprayed. Due to this, hydraulic oil is not suitable for systems where ignition is a risk. In these cases, hydraulic fluids were developed to replace hydraulic oil, offering safer performance.
Common Types of Hydraulic Oil
- General Hydraulic Oil – Good for regular machines. It resists oxidation and reduces friction.
- Wear-Resistant Hydraulic Oil – Works well in high-pressure, high-temperature machinery.
- Flame-Retardant Hydraulic Oil – Used in machines where there is a fire risk.
In short, Hydraulic oil is one kind of hydraulic fluid, but not all hydraulic fluids are oils. Hydraulic fluids are also used in applications such as automatic transmissions and are safer in situations where there is a risk of fire.
Final Takeaways
Choosing the correct fluid is crucial for your vehicle’s safety and optimal performance. Brake fluid is designed to withstand the heat, pressure, and components of your brake system, whereas hydraulic fluid is used in other machines and may not be suitable for brakes.
Always refer to your car’s manual and use the fluid recommended by your manufacturer. Regular maintenance, such as changing old or dirty brake fluid, helps keep your brakes strong and reliable. The correct fluid enables you to stop safely every time you press the pedal.
FAQs
Q1: Are hydraulic brake fluid and brake fluid the same?
Yes, they are the same. Both work to transfer force in your braking system. Always use the correct brake fluid with the right boiling point for safe performance.
Q2: Should I use DOT 3 or DOT 4 brake fluid?
DOT 3 and DOT 4 can be mixed in some cases, but DOT 4 is recommended for high-heat braking systems. Always follow your vehicle’s manual for the best choice.
Q3: How long does brake fluid last?
Sealed brake fluid has no set expiration date. Once opened, use it within three months and discard it after one year to avoid moisture contamination.
Editor-at-Large
A passionate writer in the lubricant industry, Awais Iqbal has been covering oils, greases, and industrial fluids since the start of his career. At 25, he’s already written for blogs, catalogs, and brand guides across the UAE. Awais’s insights help companies connect with their audience, and his clear, helpful writing style is trusted by brands in the region.
