When maintaining the brake system of your vehicle, you need to monitor your brake fluid color regularly. Brake fluid will take some years to go bad when you are using the brake system in the right way. Both vehicle users and drivers must know the color of brake fluid to help you in knowing exactly when the brake fluid needs to be replaced.
Brake fluid color will differ depending on the type of brake fluid you are using. Some of the things that will make a brake fluid change its color are regular heating, banging rubber brake lines, moisture, and aging.
Brake Fluid Color Guide
When replacing a master cylinder or brake pad, you need to purchase a bottle of brake fluid. There are three types of brake oils, which include DOT 3, DOT 4, DOT 5, and DOT 5.1. These brake fluids have different colors. DOT 3, DOT4, and DOT 5 brake fluids have the same color. The color will change to black or brown over time. The brake fluid color will change due to regular heating, aging rubber brake lines, moisture, and aging. Let us discuss the different brake fluids for automotive in this brake fluid color guide:
DOT 3
The DOT 3 brake fluid is a poly glycol-based product. It was among the first brake fluids to be developed, but it has lost its popularity over the years due to the introduction of more advanced brake fluids. It has a boiling point of 205°C minimum. Its wet boiling point is 140°C.
This brake fluid will absorb around one to two percent water depending on the operating conditions and climate. The brake fluid is most suitable for light trucks and domestic cars for normal driving. This brake fluid absorbs moisture from the environment, thus reducing its boiling point. DOT 3 brake fluid has a clear bluish color when it is new. It is well-compatible with all the other brake fluids apart from DOT 5.
DOT 4
This is another brake fluid based on poly glycol. It has a minimum boiling point of 230 degrees Celsius when dry and a minimum boiling point of 155 degrees Celsius when wet. The brake fluid is used for higher and medium-sized modern vehicles. It is also ideal for vehicles with ABS systems, high-speed braking systems, towing, and high altitudes.
The brake fluid also grips moisture thus reducing its ERPB (boiling point). The fluid can affect the paint of the vehicle, so you need to handle it with care. The color of the DOT 4 brake fluid is almost mineral clear with a little composition of yellow. It is compatible with DOT 3 and DOT 5.1.
DOT 5
This is a silicone-based brake fluid. It has a wet boiling point of 180°C and a dry boiling point of 260°C. It is mostly used on military vehicles and antique and weekend collector vehicles, which sit for a long time. This brake fluid is not compatible with DOT 5.1, DOT 4, and DOT 3.
It does not cause any damage to the paint of your vehicle and does not absorb water. The brake fluid is also compatible with rubber formulations. The fluid absorbs a lot of air, giving you a poor pedal feeling. It is, therefore, not ideal for racing cars because of its compressibility when faced with high temperatures.
When water gets into the DOT 5 brake fluid, it will cause gassing, freezing, and severe localized corrosion. This is because water is much heavier and does not mix with silicone fluids, making it unsuitable for ABS. This brake fluid is highly compressible under normal braking formation due to foaming and aeration. This gives you a spongy brake feel.
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DOT 5.1
DOT 5.1 brake fluid is also based on poly glycol. It has a minimum dry boiling point of 270°C and a wet boiling point of 190°C. The fluid is ideal for racecars, towing vehicles, and delivery and fleet trucks. The brake fluid can mix well with DOT 4 and DOT 3. DOT 5 has a higher boiling point than DOT 4 and DOT 3 brake fluids. This fluid also absorbs moisture from the atmosphere, thus reducing its boiling point. The brake fluid can also cause damage to the paint. DOT 5.1 brake fluid is amber in color.
FAQs
What Color Is Brake Fluid When It Leaks?
Brake fluid starts from being clear to yellowing and becomes darker with age. You might confuse brake fluid with motor oil, but the brake fluid has a more silky texture compared to oil. If you see a silky fluid leaking from the vehicle, then it is most likely the brake fluid. Leaking brake fluid is mainly clear or amber when it leaks. Some of the things that can cause a brake fluid leak are problems in the calipers, worn-out brake pads, loose bleeder valves, leaking in the master cylinder, and a faulty ABS unit.
How Do You Know When Brake Fluid Is Bad?
There are various signs of bad brake fluid. One of them is if the brake pedal starts feeling mushy and soft, making it hard for the car to stop. This is caused when moisture builds up in the brake fluid, thus causing the fluid to boil under pressure and heat of hard breaking, which causes air to be created in the brake lines. Another way to know that the brake fluid has gone bad is through its color. Bad brake fluid is brown or black. The color of the brake fluid becomes darker with age. If you notice that it has become dark, then it is time to replace it.
What Happens If Your Brake Fluid Is Dirty?
Dirty brake fluid can change the operation of your brake system. You will feel this from the brake pedal, and it can heat dissipation regularly. On top of that, having moisture in brake fluids can cause internal corrosion of the master cylinder, calipers, and brake lines. This will finally cause damage to the brake system. It is, therefore, crucial to keep on checking your brake fluid regularly and change it whenever it starts becoming dark.
Does Brake Fluid Have a Smell?
Brake fluid has a funny fishy smell similar to that of castor oil or fish oil. Having knowledge of how the brake fluid smells can help you know when it is leaking. Brake fluid leaks near the brake pedal, and thus you might notice some fishy smell in your vehicle.
What Happens If the Brake Fluid Is Not Changed?
When you fail to change the brake fluid, it absorbs moisture from the environment. Moisture-laden brake fluid can cause corrosion and rust of the metal components. This results in rust particles getting to the brake fluid, making it contaminated. Failing to change the brake fluids will affect the operating system of your brake system.
Check the brake fluid regularly for the safety of the braking system. After checking the brake system, ensure you have closed the brake fluid reservoir cap well. Failing to close it well can allow grime, debris, and dirt to get in the braking system.
Conclusion
Most of the brake fluids have a clear, yellowish, and golden color. The color of the fluids darkens as it ages, meaning that it has collected debris and absorbed moisture from the environment. The number of times you change your brake fluid depends on the type of car and how you use the brake system. Check the brake fluids regularly and note their colors. Long use of bad brake fluid reduces the performance of your car and may eventually damage the braking system and its components. If you cannot do it yourself, get a professional mechanic to check the brake fluid color and change it on your behalf to ensure the car’s safety.
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