Can You Mix Different Brands of Brake Fluid? Truth Revealed

Brake fluid is a critically important component in your car’s braking system. It plays a vital role in transferring force from the brake pedal to the brakes, ensuring you can stop quickly and safely. But here’s the question that often pops up – can you mix different brands of brake fluid?  

Here’s the quick answer:

While some manufacturers discourage mixing brake fluid brands, it is generally safe to do so as long as they are of the same DOT rating. However, there may be differences in formulation components that could affect braking performance or risk damage to hydraulic components. 

To avoid these issues, it’s best to stick with one brand. If you must mix brands, ensure you thoroughly flush out any remaining residue before bleeding each wheel cylinder properly with the new brand. 

Read on to get an in-depth explanation of how different brands can affect braking performance and the precautions you need to take when mixing them.

Understanding Brake Fluid Types and Grades

Brake fluids come in four types: DOT (Department Of Transportation) 3, 4, 5, and 5.1 – each with various boiling points and viscosity ratings. The boiling point determines how well it can withstand heat while maintaining its properties under pressure. 

This is crucial since hot and cold temperatures affect braking performance by changing the viscosity level so that it slows down or speeds up within seconds. Brake fluids with higher boiling points offer better performance, and DOT 5 is known to have the highest boiling point.

Can You Mix Different Brands of Brake Fluid?

Now that we know the different types and grades of brake fluid let’s address whether it’s possible to mix different brands.

Firstly, it’s worth noting that some manufacturers discourage mixing brands even if they have the same DOT rating. This is due to differences in formulation components, which may react differently when mixed with another brand. Thus, sticking to one brand helps ensure compatibility without reducing braking performance or risking damage to hydraulic components.

However, mixing different brands is relatively safe as long as they are of the same grade – i.e., you cannot mix Dot 3 and Dot 4 fluids without compromising on braking performance. 

When using different brands of brake fluids, ensure you thoroughly flush out any remaining residue first by bleeding each wheel cylinder properly before proceeding with the new brand. 

It’s also important not to mix synthetic and non-synthetic brake fluids as this can cause problems due to the differences in formulation.

Effects of Mixing Different Brands of Brake Fluid

While mixing different brands of brake fluids is generally safe, there are instances where it may negatively affect the brake system’s functionality:

1. Reduction in boiling point: Some brake fluids have different boiling points even if they share the same DOT rating. When mixed, lower-quality blends can bring down the overall quality of braking performance and reduce its ability to handle extreme temperatures.

2. Reduced lubrication: Brake fluid comprises specific additives that help maintain clean braking components while providing adequate amounts of lubrication. When brands with different additive formulations are mixed, it interferes with the way these additives work together, potentially leading to component damage and reduced performance levels.

3. Corrosion: Brake fluid contains a combination of chemicals that prevent corrosion within the hydraulic system. Mixing incompatible brands can lead to chemical reactions that increase corrosion risks, leading to a potentially dangerous situation that could make your brakes fail suddenly or suffer from uneven pressure.

4. Inconsistent Results: Different brands of brake fluids vary in viscosity ratings, which will affect their flow rates through hydraulic hoses, master cylinders and calipers differently. This inconsistency may affect braking responsiveness; thus leading to poor vehicle handling and safety concerns.

How Can I Ensure Compatibility When Topping Off My Brake Fluid?

As we’ve established, not all brands of brake fluid are compatible with each other. This means that if you need to top off your brake fluid, it’s crucial to ensure compatibility before doing so. Here are a few tips on how you can do this:

1. Check Your Vehicle Manual: Your vehicle manual will tell you which type and grade of brake fluid are best suited for your vehicle. This is the first and most crucial step to ensure compatibility when topping off your brake fluid.

2. Stick to One Brand: Suppose you’re unsure which brand of brake fluid is already in your brake system or worry about mixing incompatible formulations. In that case, it’s recommended to always stick with one brand of brake fluid when topping up the levels or performing a complete replacement.

3. Compare DOT Ratings: When switching between one brand of DOT-rated brake fluid and another, you should not encounter any issues as long as both brands adhere to the same specifications (e.g., DOT 3). However, it is crucial to ensure that the two brands have comparable boiling points. Mixing blends with differing boiling points could potentially reduce their capacity to handle high heat requirements.

4. Avoid Mixing Synthetic And Non-Synthetic Brake Fluids: Here’s another crucial tip to emphasize, it is imperative not to mix synthetic and non-synthetic brake fluids. Even if they share the same DOT rating, you should never combine synthetic blends with petroleum-based brands. Mixing these two formulations can result in potentially dangerous reactions.

5. Bleed The System Properly: Before topping off your brake fluid, ensure that you’ve bled all brake lines properly and got rid of any old fluid entirely. Failing to do so would result in mixing new fluid with old fluid, which is never recommended since contaminants present in old fluids can easily compromise performance or lead to system failure down the line.

How to Properly Flush Out Old Brake Fluid Before Adding a New Brand

Flushing out the old brake fluid before adding new fluid is essential to ensure that you get optimal braking performance and maintain your vehicle’s safety on the road. Failure to flush out the old fluid properly could lead to reduced braking ability, system malfunctions, or even failure. Here are some tips for flushing out old brake fluid properly:

1. Remove Old Brake Fluid from the Reservoir

Start by removing as much old brake fluid from the reservoir as possible using a suction tool such as a turkey baster. Remember never to reuse old brake fluids since these might erode important components of your car’s hydraulic system or cause contamination.

2. Bleed Each Wheel Cylinder Step by Step 

Bleeding each wheel cylinder is an essential part of flushing out old brake fluid entirely; it ensures that you remove all contaminants present in the hydraulic lines and calipers, preventing them from mixing with new brake fluids.

Here’s how to do it:

  • Start with the furthest cylinder away from the master cylinder (typically, it’s located at one of the rear wheels).
  •  Loosen the bleeder valve screw slightly while keeping hydraulic pressure tight.
  • Drain about 10 ml of fluid, then tighten the valve before restoring hydraulic pressure, ensuring that you don’t allow air or other contaminants to enter.
  • Repeat the process for all other wheel cylinders in turn.

3. Top up with New Brake Fluid

After thoroughly flushing out old brake fluid, refill the reservoir with fresh, compatible brake fluid recommended within your vehicle’s specifications until it reaches its optimal level.

4. Bleed Again

To get rid of any remaining pockets of air present in your hydraulic lines and calipers, bleed each wheel cylinder again after replacing your new brake fluid. This will ensure that you have an efficient braking system without air pockets that affect braking performance. 

5. Test Your Brakes

Lastly, test your brakes by conducting a road test, starting slowly and gently applying the brake pedal to see if it is responsive and consistent throughout its range of motion. If you suspect an issue or notice any inconsistencies with braking feel or responsiveness, take your vehicle for a thorough inspection at a professional workshop.


In conclusion, you can mix different brands of brake fluids as long as they are the same DOT rating. 

However, be careful because some brake fluid types don’t mix well together. Mixing two incompatible formulations can result in less than desirable results that range from unwanted effects on your car’s braking performance to potential safety risks.

Therefore, it is always best practice not to mix different brake fluid brands unless required or recommended by a manufacturer explicitly. If you need to top up or bleed out old fluid from the system, choose a product within the same brand before replacing brake fluid completely.

If unsure about the best brake fluid for your vehicle, ask a professional mechanic to help choose the right product and ensure your brakes work safely.

Similar Posts