Can you mix synthetic and regular brake fluid? No, mixing synthetic and regular brake fluid can cause performance issues and damage the brake system. Always use the recommended fluid type for your vehicle.
Brake fluid is an important part of a vehicle’s brake system. With time, brake fluid may lose its effectiveness, because of contamination, moisture absorption, or degradation from heat. This leads to the question, Can you mix synthetic brake fluid and regular brake fluid? This seems like a short and easy solution, but it can lead to damaging the braking system.
This article breaks down the specifics of both regular and synthetic brake fluid, the risk of mixing them, and how to maintain your braking system.
Contents
Regular Brake Fluid
Regular brake fluid, also known as mineral oil-based fluid, is made from both organic and inorganic compounds. It is used in vehicles without advanced braking systems. This fluid is glycol-ether-based, combining glycol and ether. It is categorized into DOT 3, DOT 4, and DOT 5 fluids. DOT stands for the Department of Transportation, the federal agency regulating U.S. transportation.
These brake fluids are hygroscopic, meaning they absorb moisture from the air. As moisture is absorbed, the fluid’s boiling point drops, which can cause brake fade.
Regular Brake Fluid Characteristics
In the operation of the braking systems of vehicles, the regular brake fluid is quite crucial in the process. The liquid is a product of a mixture of both organic and inorganic fluids. The combination gives the mix a composition and flexibility feature that allows the liquid to adapt to the operation of regular braking systems.
To identify the main features that describe regular brake fluid, let’s examine them in further detail.
- Moisture Absorption – The fluid absorbs moisture from the environment, leading to a reduction in its boiling point.
- Boiling Point – Heavy braking can lead to the liquid being subjected to extreme situations that will result in the liquid getting overheated leading to vaporization. Regular brake fluids have lower boiling points than synthetic brake fluids.
- Corrosion Risks: Brake fluid absorbs moisture over time, leading to rust and corrosion throughout the entire braking system. This can damage key components like the master cylinder, calipers, and brake lines.
What is Synthetic Brake Fluid?
Synthetic brake fluid is used in the latest vehicles with the best braking systems (ABS). Also, it is utilized in high-end vehicles such as sports cars. The main differentiation between synthetic and normal brake fluid is in their chemical composition. Regular brake fluid is glycol-based, and synthetic fluid is made from polyglycol ethers or other chemical compounds.
Synthetic brake fluid is better at withstanding high temperatures, and it is more absorbent and moisture resistant than normal brake fluid. Because of these reasons, it is more applicable in modern vehicles than regular brake fluid.
Properties of Synthetic Brake Fluid
Compared to regular brake fluid, synthetic brake fluid has more benefits, specifically for extreme conditions. Customarily, using synthetic brake fluid, a vehicle can be expected to perform under more extreme, higher (not temperature, but stress related) performance conditions.
Let’s proceed to uncover some of the more extreme and passionate characteristics.
- Higher boiling point: Synthetic brake fluid is more likely to withstand higher temperatures since it has higher boiling point. Because of these reasons, a vehicle can be expected to provide more extreme performance conditions compared to regular brake fuel.
- Less moisture absorption: Synthetic fluids absorb less moisture, which helps keep a higher boiling point, as well as preventing corrosion.
- Enhanced braking: Synthetic brake fluids are engineered for high performance, so they enhance braking, especially during heavy, repeated braking.
Can You Mix Synthetic and Regular Brake Fluid?
There can be problems when mixing different types of brake fluid. In this section, we will examine the use of regular versus synthetic brake fluid as well as the issues that can arise when you don’t use the correct fluid in your braking system.
1. Chemical Incompatibility
One of the main reasons to keep the two types of brake fluid separated is the chemical incompatibility. Brake fluids are both regular and synthetic, and the formulas are different, as well as their performance characteristics. For example, synthetic fluid may be less effective than regular in terms of performance, but it will break down less quickly than regular.
The use of regular fluids could cause synthetic to break down more quickly. The regular fluid may even lead to contamination and greater brake fluid use, which could cause overall poor braking performance.
2. Decreased Boiling Point
One key difference between synthetic and regular brake fluid is the boiling point. Regular brake fluid has a lower boiling point than synthetic fluid. Regular fluid usually boils around 400°F (204°C). Synthetic fluid can exceed 500°F (260°C). When brake fluid boils, it turns into vapor. Vapor is compressible and reduces braking performance. Mixing both fluids can lower the overall boiling point. This increases the risk of brake fade and possible brake system failure.
3. Moisture Absorption and Contamination
Regular brake fluid, as explained above, is a hygroscopic fluid. This means that it absorbs moisture from the air around it. When moisture is introduced into the fluid, it can promote corrosion and reduce the boiling point of the fluid. In contrast, synthetic brake fluids absorb moisture to a lesser extent. Because of this, the internal components of synthetic brake fluids can resist rusting better than regular brake fluids.
If you mix synthetic brake fluid with normal brake fluid, the synthetic brake fluid can become moisture-contaminated because normal brake fluid absorbs water. Because of the contamination, fluid performance can be decreased, leading to increased corrosion risk to the brake system, and potentially the brake lines clogging. In high performance cars where the brakes are relied on heavily, mixing brake fluids can be very dangerous.
4. Possible Harm to the Components of the Brake System
The brake systems are meant to work with certain types of fluids. Mixing brake fluids with different chemical compositions can cause damage to the components of the brake system. Seals, hoses and gaskets within the braking system may be incompatible with synthetic fluid and cause fluid leaks. This can lead to a loss of brake fluid and braking power or even a complete system failure.
To make things worse, mixing fluids can leave contaminants and residue in the brake lines which can lead to a less effective braking system and wearing out brake pads and calipers.
5. Soft Brake Pedal and Loss of Performance
You may notice that your brake pedal feels soft after mixing brake fluids, both regular and synthetic. This could be due to the presence of small air bubbles, caused by the two fluids reacting because of a chemical hazard. These bubbles can form in the brake lines. This would cause a decrease in the brake fluid’s ability to be compressed, giving an inconsistent performance. While braking, it may be difficult to achieve the feel you want, especially if hard braking is needed.
How to Fix Mixed Brake Fluids
In the event that you have mixed synthetic and regular brake fluid, the most appropriate thing to do would be to immediately flush the entire brake system. This would be removing the contaminated fluid, cleaning the brake lines and replacing the old fluid with the correct brake fluid for your system.
Steps to Fix the Situation
To prevent any damage to the braking system, if you have mixed synthetic and regular brake fluids, you will need to take care of the problem urgently. These are the steps you have to take to ensure that your brakes work properly.
- Do a Brake Fluid Flush: This shall get rid of all mixed fluids in the system.
- Look for Leaks: Inspect the braking system for damage, leaks, or signs of deterioration in the braking system seals.
- Replenish with Proper Fluid: After flushing the system, put in the type of brake fluid (synthetic or regular) that the car manufacturer specifies.
- Examine and Test the Braking System: After working on the brake system, examine and test all components to verify they perform as required.
When to Use Synthetic Brake Fluid?
The use of synthetic brake fluid is frequently recommended when regular brake fluid is not effective, including:
High-Performance Vehicles: For brake systems in sports cars and other aggressive driving/racing vehicles, performance is critical. Because of its better boiling point and heat resistance, these vehicles perform better with synthetic brake fluid.
Vehicles in Hot or Humid Climates: If you live in an area with high humidity or heat, synthetic brake fluid is the better choice. Its ability to resist moisture makes it less likely to break down, and it also better preserves the brake system overall.
Modern Vehicles Equipped With Advanced Braking Systems: Most modern vehicles come with advanced braking systems like anti-lock braking systems (ABS). These may use synthetic brake fluid in order to function at their best. Check the manual for your specific vehicle for recommendations.
Frequently Asked Questions
Here are some FAQs about mixing synthetic and regular brake fluid –
1. How do I know if my brake fluid is synthetic or regular?
Inspect the container’s label. Synthetic brake fluid is marked as “synthetic” or “DOT 4/5.1.” Regular brake fluid is marked as “DOT 3” or “mineral-based.”
2. Is it okay to use synthetic brake fluid in older cars?
Using synthetic brake fluid in older cars is fine, but it’s best to check with the vehicle’s owner’s manual for the manufacturer’s guidelines, as some older cars may only accept regular brake fluid.
3. How often should I replace my brake fluid?
Depending on your vehicle and the type of brake fluid, you should replace your brake fluid about every 30,000 to 50,000 miles or every 2 to 3 years.
Conclusion
To sum up, due to the differences in chemical properties, the mixing of synthetic and regular brake fluid is inadvisable. Both brake fluids serve similar purposes, and mixing them can lead to compromised braking performance, moisture absorption, damage to brake fluid, and system damage. In the worst-case scenario, this can lead to catastrophic situations.
Always use what is recommended by the manufacturers for your vehicle. If there is any mixing of brake fluids by accident, flush the brake fluids as soon as possible. Taking care of your brakes will keep your car safe, as well as the whole brake system. It’ll keep your braking system in working order for an extended period of time.
