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Dot 3 vs Dot 4 Brake Fluid

Brake fluid is a hydraulic liquid that helps move the brake pedal to engage the brake pads and stop the car. It also provides lubrication and avoids rust, supporting the correct operation of brakes. In this detailed blog, we will examine these liquids in depth.

The United States Transportation Department determines the standards for brake fluids, establishes regulations to dictate their performance, and classifies them into various dot categories. Dot 3 and Dot 4 are regular vehicles’ most frequently used types of brake fluids.

Dot 3 Brake Fluid

Dot 3 fluid is a more traditional and widespread variety, fitting many brake systems. The point at which it starts to boil and become steam is lower than DOT 4’s temperature. This specific temperature is called the boiling point. When you feel the brake fade, the brake pedal gets softer and does not react appropriately.

Dot 4 Brake Fluid

Dot 4 fluid has higher boiling points than Dot 3, improving performance during intense driving. Therefore, individuals frequently select it for high-performance vehicles when extensive towing is needed and in circumstances that demand frequent braking, like descending steep mountain paths.

Dot 4 fluid absorbs moisture from the air slightly faster than Dot 3. It might seem like a downside, but water absorption decreases the fluid’s boiling point over time. Change your brake fluid every two years to have the best brake performance.

Boiling Points of Brake Fluid Explained:

There are two types of boiling points in brake fluids:

  • Dry Boiling Point: The boiling point of the fresh, unopened brake fluid.
  • Wet Boiling Point: The boiling point decreases as brake fluid absorbs moisture over time.

Critical Differences Between Dot 3 and Dot 4 Brake Fluids

dot 3 vs dot 4 brake fluid

1. Composition and Characteristics:

Dot 3 and Dot 4 are fluid types made from glycol-ether. Dot 4 may include additional substances to enhance its performance.

2. Performance:

Dot 4 is more resistant to high temperatures because it boils at higher points, both dry and wet, as described next.

3. Boiling Points:

  • DOT 3:
    • Dry Boiling Point: Typically around 401°F (205°C).
    • Wet Boiling Point: Typically around 284°F (140°C).
  • DOT 4:
    • Dry Boiling Point: Typically around 446°F (230°C).
    • Wet Boiling Point: Typically around 311°F (155°C).

4. Moisture Absorption Rates:

Dot 4 typically absorbs moisture quicker than dot 3. Nonetheless, they both need consistent replacement to maintain their best performance.

Choosing the Right Dot Rating for Your Vehicle

When to Use Dot 3:

  • Typical cars for daily transport usually have standard systems to stop the vehicle.
  • Previously, the vehicles initially used Dot 3 liquid.
  • Situations where the car experiences moderate braking conditions.

When to Use Dot 4:

  • High-performance vehicles with high-performance braking systems.
  • Vehicles used for towing or hauling heavy loads.
  • If you often drive in the city where you must stop and start a lot, or if you have a way of driving that is quite forceful.
  • Please check the car’s manual to see what dot rating they suggest.


Can I mix Dot 3 and Dot 4 brake fluid?

Yes, they usually work together. But it’s better to clean all the old fluid before you put in a new one.

How often should I change my brake fluid?

Replace it after every two years or after spanning 30,000 miles.

Can I use Dot 4 Instead of Dot 3?

Yes, I am, generally speaking. Dot 4 can replace Dot 3 in systems because it works better.


Knowing the differences between Dot 3 and Dot 4 brake fluids is crucial for keeping brakes well. While Dot 3 works fine for regular cars, Dot 4 is better for fast or heavy vehicles. Shields Oil, known for suitable lubricants, provides both types of brake fluids to meet different car needs. Shields Oil suggests that changing fluids often helps keep the brakes working well and safe when driving.

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