Because of different chemical compositions, these two brake fluids are incompatible with each other, which means it’s not possible to mix them. Mixing them together can lead to brake failure.

Now let’s cover the next type of brake fluid which is the DOT 4 type of brake fluid. The DOT 4 brake fluid is a slight improvement over the DOT 3 but not as such as the DOT 5 brake fluid. Although at Dandy Classics we are always interested in innovative products for classic cars, we have a rather traditional approach in our workshop. Our cars were designed to be serviced in a certain way, and one needs to respect that while also taking into account the many innovations in lubricants, coolants and other fluids. Take DOT 5 brake fluid for example. In theory, this is a perfect product for our classics. It is not agressive to paint and does not attract moisture. This means that in principle the brake fluid will never have to be replaced.

DOT 5 only covers silicone-based brake fluid, with a fresh boiling point of 500 degrees Fahrenheit (260⁰C). For the same brake fluid in a wet state, it’s 356 degrees Fahrenheit (180⁰C).

DOT 5 brake fluid is a silicon-based fluid . This was developed to be used in cars where moisture was definitely going to be prevalent and unavoidable. That means things like high performance vehicles and military vehicles. It has a very high boiling point, but it also has more compressibility than the glycol ether-based fluids. Also, there are now DOT4 brake fluids that have boiling points that are actually above DOT 5 brake fluid so there aren't a lot of reasons for you to look into getting a DOT 5 fluid for your car if you don’t need it. When it comes to changing from one to another fluid we would not recommend you to do so. Even though it is possible to do this type of work on your car. The Mobil Brake Fluid DOT 5.1 500ml is a high-performance brake fluid. This is suitable for all disc, drum and anti-skid braking systems used in average to high-performance vehicles requiring DOT 3 or DOT 4 level performance. It is based on polyethylene glycol ether technology to provide the highest level of brake and clutch performance in modern as well as older model automotive and commercial vehicles. This is a synthetic fluid for hydraulic braking systems.

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As well as brake fluids from leading brands like Comma, Mobil and Wynss, our Vizibleed aid makes draining the existing fluid safer and easier. Before replacing the fluid, use a Halfords brake cleaner to flush out the system, ensuring peak performance from your new fluid. While on the other hand DOT 3 is not interchangeable with DOT 5 brake fluid. These two are completely different and do not overlap. So, if your car is not certified for DOT 5, you should avoid using it and instead use the 5.1 fluid instead. This will guarantee that you get the best performance for your money. Additionally, if your vehicle isn’t designed for DOT 5 brake fluid and you try to use it even after a full flush. You might still end up with a problematic brake system.

Since they are glycol-based fluids, you can use DOT 5.1 in place for DOT 3. However, it's always better to adhere to your car manufacturer's manual for the recommended type of brake fluid. On the downside, DOT 5.1 will absorb water, it eats paints, and it is also more expensive than DOT 3 and DOT 4. This brake fluid is also challenging to find in some auto parts stores. The brake fluid is not compatible with DOT 5, and you should never mix it for any reason. DOT 3 vs. DOT 4 Brake Fluid: Which One Is The Better Brake Fluid? Brake fluids must maintain a low level of compressibility, even with varying temperatures to accommodate different environmental conditions. This is important to ensure consistent brake pedal feel. As compressibility increases, more brake pedal travel is necessary for the same amount of brake caliper piston force.

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This fluid is purple in color. Unlike other brake fluids which are clear in color. This way you will never mix them and possibly ruin the braking system on your car. Can You Mix DOT 3 And DOT 5 Brake Fluid The answer is a big NO! Like earlier explained, DOT 5 is silicone-based fluid, while DOT 5.1 is glycol-based fluid. This means that they are not compatible and can not be mixed. Mixing them will corrode the components of the braking system and will cause brake failures. However, you can mix DOT 5.1 with DOT 3 and DOT 4 without causing your brake system any harm. This type of fluid is different in a lot of things in comparison to the DOT 5. Namely, it is different in its structure.

As we have seen, DOT 5 brake fluid has one of the highest boiling points of all the fluids available. Typically, your car will run on either a DOT3 or a DOT4 brake fluid which are both glycol ether-based brake fluids. The brake fluid reservoir is usually white, and you should be able to see the dark brake fluid through the container. Before we dive into more complex topics such as the DOT 5 brake fluid, let’s first take a look at the basics of the brake fluid and also learn what this DOT abbreviation means in the first place. Knowing this will be a good starting point for beginners who are not into cars and want to learn the basic stuff. Please read the following section, ‘Understanding Brake Fluids’ is an easy to understand guide explaining brake fluid. This is ok for drivers who only use their cars at the race circuit. Ordinary drivers who frequently drive their cars on ordinary streets should be more concerned if their fluid meets DOT specification. Brake fluid that do not meet DOT specification can speed up the deterioration of brake components over a extended period time. It can also lead to the malfunctioning of ABS during cold weather. Most people do not know much about brake fluid, and it can be hard to find relevant information to learn more about it.

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Although DOT 5 Brake fluid comes with high boiling points and performs well in extreme temperatures. It’s more compressible than the DOT 4 and any other type of brake fluid that’s based on glycol ether. So, what is brake fluid in general? The brake fluid is simply a hydraulic fluid that is used for brake system applications. The minimum boiling point of DOT 5.1 fluid is 270 degrees celsius when dry and 190 degrees celsius when wet (ie. some water has ingressed into the system).