Is DOT 4 brake fluid compatible with DOT 3 brake fluid?
When it comes to maintaining your vehicle's braking system, understanding the compatibility of brake fluids is crucial. At Kevin's Autos, we often get asked whether DOT 4 brake fluid can be used in a system designed for DOT 3. In this article, we’ll break down the differences between these two types of brake fluid and explain their compatibility.
Understanding DOT 3 and DOT 4 Brake Fluids
Both DOT 3 and DOT 4 brake fluids are glycol-based fluids commonly used in automotive braking systems. They are designed to perform under high temperatures and pressures, ensuring your brakes function effectively. However, there are some key differences between the two:
- Boiling Point: DOT 4 brake fluid has a higher boiling point compared to DOT 3, making it more suitable for high-performance or heavy-duty applications.
- Moisture Absorption: Both fluids are hygroscopic, meaning they absorb moisture over time, but DOT 4 tends to absorb moisture slightly faster than DOT 3.
- Chemical Composition: DOT 4 contains additional additives to enhance its performance under extreme conditions.
Compatibility of DOT 4 with DOT 3
The good news is that DOT 4 brake fluid is compatible with DOT 3 systems. This means you can safely use DOT 4 in a system originally designed for DOT 3. However, there are a few important considerations to keep in mind:
- Mixing Fluids: While DOT 4 can be mixed with DOT 3, doing so may slightly lower the overall boiling point of the fluid. If you’re upgrading to DOT 4, it’s best to flush the system completely to ensure optimal performance.
- Performance Benefits: Upgrading to DOT 4 can provide better performance, especially in situations where the brakes are subjected to high heat, such as towing or spirited driving.
- Maintenance: Since DOT 4 absorbs moisture more quickly, it may require more frequent replacement compared to DOT 3.
When Should You Use DOT 4 Instead of DOT 3?
While DOT 3 is sufficient for most everyday driving conditions, there are scenarios where DOT 4 is the better choice:
- If you frequently drive in mountainous areas or other environments that require heavy braking.
- If you use your vehicle for towing or hauling heavy loads.
- If you participate in high-performance driving or track days.
Conclusion
In summary, DOT 4 brake fluid is compatible with DOT 3 systems and can be a beneficial upgrade in certain situations. However, it’s important to flush the system when switching to ensure maximum performance and safety. At Kevin's Autos, we recommend consulting with a professional mechanic to determine the best brake fluid for your vehicle’s needs. If you have any questions or need assistance, feel free to reach out to us!
Frequently Asked Questions
Is super dot 4 compatible with DOT 3?
SUPER DOT 4 BRAKE FLUID is suitable for use where the vehicle manufacturer specifies DOT 3 or DOT 4 brake fluid. SUPER DOT 4 BRAKE FLUID should be changed according to the manufacturers service specifications. SUPER DOT 4 BRAKE FLUID can be used for first fill or refilling a brake or clutch system.
Is it okay to mix DOT 3 and DOT 4 brake fluid?
Yes. DOT 3 and DOT 4 are both glycol ether based, and will mix just fine. DOT 4 has a higher boiling point, so depending on the application, it may be necessary to use that instead of DOT 3. Do not mix DOT 5 with either of them, as it is silicone based.
Can you interchange DOT 3 and DOT 4?
Yes. DOT 3 brake fluid is compatible with DOT 4 brake fluid. However, DOT 4 offers a higher boiling point.
What happens if you mix brake fluid?
Adding a lower specification brake fluid into that of a higher one lowers the boiling point of the latter and weakens its resistance to absorbing moisture.
What happens if you mix different types of brake fluid?
Adding a lower specification brake fluid into that of a higher one lowers the boiling point of the latter and weakens its resistance to absorbing moisture.
Can I use DOT 5.1 instead of DOT 3?
Only use DOT 5 in a completely dry system or in a vehicle that already has DOT 5 in the system. DOT 3, DOT 4 and DOT 5.1 are all interchangeable. Boiling points are the most critical aspect of brake fluid to keep an eye on.
What is the difference between DOT 3 and DOT 4 brake fluid?
The primary differences between the two include the following: DOT 3 brake fluid will absorb less water than DOT 4 from the air over time, meaning you'll need to have your fluid changed less frequently. DOT 4 brake fluid has higher dry and wet boiling points, making it safer for higher temperatures. Cheers!!
What is an alternative for DOT 3 brake fluid?
Since Mineral Oil is hydrophobic and does not absorb water from its environment, one of the great advantages it has over DOT fluid is that once opened it can be stored indefinitely.
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 DOT 3 instead of DOT 4 in emergency?
If you're considering topping up the brake fluid, mixing small amounts of DOT 3 and DOT 4 in an emergency might be acceptable. However, if you're planning a brake fluid change or flush, it's recommended to use one type of fluid consistently to maintain the fluid's properties.
