Many car enthusiasts ask about the consequences of mixing different brake fluids. Yes, it’s safe to mix brake fluids of different brands, but they need to be of the same grade.
When brake fluids of the same grade are mixed, let’s say, DOT 3 and 4, the worst that can happen is having a brake fluid with a lower boiling point. DOT specifications show the boiling points of the fluids and not necessarily who manufactures them.
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What brake fluids DOT can be mixed?
One can safely mix DOT 3, 4, or 5.1, as they have the same glycol-ether base. However, it is important to keep a note of the lowest DOT number.
It is advised to avoid mixing DOT 5 with any other DOT fluid. It is largely used by heavy vehicles and also used by racing cars, as it has a silicone base. A silicone-based fluid is not compatible with anti-locking brake systems (ABS). This is the main reason you should not mix a DOT 5 with other brake fluids.
DOT 3 is compatible with DOT 4. You should have it at the back of your mind. DOT 4 has a high boiling compared to DOT 3. Hence, the resulting mixture will have a lower boiling point.
DOT 5.1 is associated with heavy-duty vehicles and high-performance cars because of its higher boiling point. Also, it can be safely mixed with DOT 3 and 4.
DOT 5 is made of a water-resistant silicone base, and it’s not compatible with other fluids. The brake fluid is suitable for cars with a high load, and it can remain packed for a long period. Thus, when mixing brake fluids, take caution of their individual properties and not brand some fluids that are not compatible.
Can you mix old and new brake fluid?
We have established specific brake fluid brands are not important for mixing brake fluids. If brake fluids have similar ingredients, they can be easily mixed.
The next question most people ask is can one add new brake fluid to old brake fluid? You may not mix a new brake fluid with an old one. If you mix the two, you are compromising the safety of your braking system.
When you have fluids with similar ingredients, you are only allowed to mix two fluids if they are new. Besides, if you mix brake fluids with different ingredients, the braking system will be a mess, and it will result in a poor fluid.
A worn brake fluid loses its beneficial properties in time so mixing it with a newer fluid will not rise the quality of the resulting, instead, it will increase the volume, a heads up when changing the brakes and discs because it may cause the fluid to overfill and make a mess in the engine compartment.
When mixing brake fluids, your primary goal should mix brake fluids that have similar ingredients. Since brake fluids are prone to absorbing water, you should do it after the recommended time.
Thus, if you mix an old brake fluid with a new one, you will have a faulty braking system. Never re-use a braking fluid, as it is an essential component in the safety of your vehicle.
When braking a vehicle, it causes a lot of heat on the baking pads, which transfer it to the braking fluid. If the braking fluid is contaminated with water, heat causes the water to evaporate and, as a result, will affect the effectiveness system.
Can you drive with mixed brake fluids for long?
Mixing brakes fluids alters their boiling point and lowers their resistance to mixing with vapor. Thus, when you are mixing a DOT 3 with a DOT 4 or DOT 5.1 you will have a blend that will not serve you for a long time.
If you mix brake fluids, you will not drive with the blend for long as it’s likely to absorb moisture and lower its effectiveness in stopping the vehicle.
Avoid driving your vehicle with mixed brake fluids unless you have an emergency where the brake fluid level is low, and you need to drive and have no access to your preferred fluid.
Besides, if you have to mix two brake fluids blend DOT 4 with DOT 3 it will have less difference in performance. But if your vehicle uses DOT 5.1, mixing it with DOT 3 will significantly lower the vehicle’s performance.
Since a brake fluid stops a vehicle by transferring force applied on the brake pedal into pressure, you must ensure the fluid remains pure.
The braking process produces a lot of heat because of friction, and in return, it heats the baking fluid. Any significant change in its properties will lower its effectiveness and one cannot drive for long with it.
If moisture gets into the vehicle, the boiling point is lowered as water will turn to vapor, which is not easily compressible, leading to an ineffective braking system.
If you mix different types of brake fluid DOT, when arriving at the destination the first thing to do is to get to a mechanic, flush the braking system and install a new brake fluid recommended by the car manufacturer.
What brake fluids DOT cannot be mixed?
You should always remember different braking fluids are made for different purposes using varying ingredients. Also, keep in mind we do not have authentic and non-synthetic brake fluids.
Glycol-based brake fluids are classified as non-synthetic and are compatible with DOT 3 except for DOT 5, which is synthetic. Thus, if you are changing your braking fluid to DOT 5, you need to flush the braking system.
However, keep in mind when mixing braking fluids, pay attention to the DOT numbers and ingredients used in their manufacture. DOT ratings show the boiling point of a braking fluid and its water-resistant capabilities.
So when you read about glycol-based braking fluids such as DOT 3, 4, and 5.1 you can easily blend them, noticing no significant change in performance.
Adding a braking fluid with a higher DOT number translates to raising the boiling point of the fluid. The blend will be a half-baked product and losses its effectiveness over time.
Thus, if you consider blending braking fluids with different DOT ratings, you should have a short-term goal of switching to a fluid with a higher rating.
Besides, you are not obliged to flush the braking system if you are moving from DOT 3 to DOT 4, but it’s recommended. if you are considering switching to braking fluid with a DOT 5, flash the braking system.
Finally, when mixing different brake fluids, pay attention to their individual properties and not brand. Ingredients used in making the fluids are an important element in determining their purposes and compatibility. Thus, you are only allowed to mix braking fluids that are compatible.
