Can You Mix Synthetic Brake Fluid With Regular Brake Fluid

can you mix synthetic brake fluid with regular brake fluid

Your brake fluid is important to help with braking, ensuring you always get where you want to go safely. As part of maintaining your car, you may at some point need to change or top up the brake fluid. The most important question would be, can you mix the synthetic brake fluid with the regular brake fluid?

It is not advisable to mix the regular and synthetic brake fluids. This is because they do have different chemical components that do not mix. So, before adding brake fluid to your car, check to confirm which type it is and if it will work well for your car.

Synthetic vs. Regular Brake Fluids

Maybe you are new to brake fluids and have no idea what each term means. Well, regular brake fluids are made using a glycol base. This is a combination of various ingredients, including glycerin and alcohol. Such types of regular brake fluids are:

  • DOT 3
  • DOT 4
  • DOT 5.1

These are the commonly used brake fluids, and you would get them as affordable options compared to using synthetic brake fluids. It is for this reason they would be readily available at different auto-parts stores.

Regular brake fluids are mostly yellow or brown in color. This is enough to help you distinguish between them and synthetic brake fluids. The DOT 5 brake fluid, which is synthetic, would have a purple color. It is so easy to now know which is which to avoid mixing them.

Below is a video explaining the differences between different brake fluids

How about synthetic brake fluids?

The synthetic brake fluids are made using a silicone base. The best example is DOT 5. Do not confuse it with DOT 5.1. In such a case, the brake fluid is made of synthetic material rather than what we see in regular brake fluids.

Brake Fluids that Can Mix

We have already established that it would not be good to mix the regular and synthetic fluids. However, which brake fluids can be mixed?

The quickest answer is that you can mix the regular brake fluids because they have the same glycol chemical component. This means that you can mix DOT 3, DOT 4, and DOT 5.1 brake fluids.

When you mix these three types of brake fluids, not much will change in performance. However, take note that a few properties will change. An example is that you would have a higher boiling point if you added brake fluid with a higher DOT rating. It can also be vice versa.

You should only mix the brake fluids if you intend to raise the boiling temperature to work well for various applications, including hard stopping.

We recommend that you always consider using one type of brake fluid rather than mixing them. This at least leaves you with consistent brake system performance.

Is the Synthetic Brake Fluid Better than Regular Brake Fluids

Is the Synthetic Brake Fluid Better than Regular Brake Fluids

You might have used synthetic engine oil before, and it was recommended as the better option because it takes longer to service the car again. You might be thinking it is the same thing here too.

It depends on the application. There are times you would need the synthetic brake fluid and when the regular brake fluid still does a good job.

The regular brake fluid is made to work with various cars without a problem. The best part is that such brake fluid also comes with a high boiling point, which is good enough for regular car driving. That is why DOT 3 brake fluid is readily available and would be affordable too.

Synthetic brake fluid is still good too. The biggest selling point would be that it has a boiling point of 500 degrees Celsius. That is not what you get with the other brake fluids. This means it can handle more aggressive braking. As such, it would be a good pick for race cars.

Take note that the passenger cars have ABS. The DOT-5 brake fluid does not work with the ABS system. You will not always find DOT-5 in modern cars because of such incompatibility issues.

Synthetic Brake Fluid Durability

If the synthetic brake fluid is as good as the manufacturer claims, how long will it last? Because of the silicon ingredients, we find that such brake fluids would last longer. It is expected that it can last 3 years before going bad.

On the other hand, regular brake fluids might not last as long. They must be changed after two years to ensure their performance is still the best.

Here is a video on brake fluids and how to choose the best one


Does the synthetic brake fluid absorb water?

Yes, it is possible that it can absorb moisture, but it would be in a lesser amount than what you get with regular brake floods.

Are DOT 4 brake fluids all the same?

So long as it has the label DOT 4, then they are the same. This is because they are made using glycol as the main ingredient. This allows you to mix it with other regular brake fluids without a problem.

Are synthetic brake fluids expensive?

Synthetic brake fluid costs $20 to $45, depending on the brand. This can be seen as expensive compared to regular brake fluids costing less than $15.

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