Is DOT 3 and dot 4 brake fluid?
Brake fluid is a critical component of a vehicle's braking system, responsible for transmitting the force applied to the brake pedal to the brake calipers, causing the pads to grip the rotors and slow or stop the vehicle. DOT 3 and DOT 4 are two of the most common types of brake fluid, but they have distinct differences that are important to understand.
What is DOT 3 Brake Fluid?
DOT 3 brake fluid is a glycol-based fluid that is hygroscopic, meaning it absorbs moisture from the air over time. This absorption can lead to a lowering of the fluid's boiling point, which can be dangerous during heavy braking or prolonged use. DOT 3 brake fluid typically has a dry boiling point of around 401°F (205°C) and a wet boiling point of around 284°F (140°C). DOT 3 brake fluid is generally recommended for use in older vehicles or those with less demanding braking systems.
What is DOT 4 Brake Fluid?
DOT 4 brake fluid is also a glycol-based fluid, but it has a higher boiling point than DOT 3. DOT 4 has a dry boiling point of around 446°F (230°C) and a wet boiling point of around 311°F (155°C). DOT 4 brake fluid is designed for use in vehicles with more demanding braking systems, such as those with anti-lock braking systems (ABS) or high-performance brakes. It is less hygroscopic than DOT 3, meaning it absorbs moisture more slowly, which helps maintain its high boiling point over time.
Key Differences Between DOT 3 and DOT 4 Brake Fluid
- Boiling Point: DOT 4 has a higher dry and wet boiling point than DOT 3, making it better suited for high-performance braking systems.
- Hygroscopicity: DOT 4 is less hygroscopic than DOT 3, meaning it absorbs moisture more slowly, which helps maintain its high boiling point over time.
- Compatibility: DOT 3 and DOT 4 brake fluids are not completely compatible and should not be mixed. Using the wrong type of brake fluid can damage the vehicle's braking system.
- Recommended Use: DOT 3 is generally recommended for older vehicles or those with less demanding braking systems, while DOT 4 is designed for use in vehicles with more advanced braking systems.
In summary, while both DOT 3 and DOT 4 brake fluids serve the same basic function, their differences in boiling point, hygroscopicity, and compatibility make them suitable for different types of vehicles and braking systems. It's important to consult your vehicle's owner's manual or a qualified mechanic to determine the appropriate brake fluid for your specific vehicle.
Can I use DOT 4 brake fluid in older cars?
Choosing the Best Brake Fluid for Your Classic Car
We recommend DOT 3 or DOT 4 because these brake fluids are glycol-based and hygroscopic. They are the kindest on your braking system.
Can I use Super DOT 4 instead of DOT 3?
SUPER DOT 4 BRAKE FLUID is suitable for use where the vehicle manufacturer specifies DOT 3 or DOT 4 brake fluid.
How to do a brake flush?
Flushing Brake Fluid
- On a level surface, set the car in gear and place a stop behind the tires to keep it from rolling.
- Open the hood and locate the master cylinder.
- Using a turkey baster, suck out all the fluid.
- Refill the reservoir back up to the fill line using fresh brake fluid.
How do I know if I need DOT 3 or DOT 4 brake fluid?
DOT 4 brake fluid has higher wet/dry boiling points than DOT 3, making it a better choice for higher temperature braking applications, like in high-performance vehicles.
Is it OK to mix old and new brake fluid?
Or, is mix of different grade fluid ? Basically, not recommended.
Are DOT 3 and DOT 4 compatible?
Yes. DOT 3 brake fluid is compatible with DOT 4 brake fluid. However, DOT 4 offers a higher boiling point. DOT 5.1 is used in high-performance and heavy-duty applications due to its high boiling point.
Does DOT 4 brake fluid have a higher boiling point than DOT 3?
DOT 3 and DOT 4 brake fluid formulas actually have different recommended service increments. DOT 3 brake fluid typically has lower boiling point temperatures, thus moisture is absorbed into the brake fluid more quickly than DOT 4.
What does DOT 3 brake fluid look like?
DOT 3 Brake fluid: Typically in clear, yellow, blue, and red shades. DOT 4 Brake fluid: Typically in light yellow or crimson red shades. DOT 5 Brake fluid: Typically in purple shades. DOT 5.1 Brake fluid: Typically in clear, yellow, and blue shades.
What happens if you mix DOT 3 and DOT 4 brake fluid?
Dot 3 and Dot 4 brake fluid are compatible with each other if you want to mix them. There will be no negative impacts from mixing the two and the brakes will still function as normal.
What vehicles use DOT 4 brake fluid?
DOT 4 is used in some euro and domestic vehicles. DOT 4 Plus is used in Mercedes and Volvo. DOT 4 Low Viscosity is used in some BMW models. Finally, DOT 4 Racing usually has an added blue color.
