Unlike glycol based DOT 3,4 and 5.1 fluids, DOT 5 silicone brake fluid will not absorb water from the atmosphere or act like a paint remover. Silicone has very high dry and wet boiling points. It is also more compressible and can absorb more air than a conventional brake fluid. In fact, there are some modern DOT 4 brake fluids available that even offer higher boiling points than the DOT 5 brake fluid. So, it’s not advisable to switch to DOT 5 if you use DOT 4 brake fluid for your vehicle. How simple is removing some to reduce the level? Is it as simple as taking the cap off and using a syringe to take fluid out of the tank, then replacing the cap, or is it always necessary to bleed the brakes? Hydragas and Hydrolastic suspension were a widely used form of hydropneumatic suspension, designed by Alex Moulton, and used on British Leyland cars from the 1960s. This system was not engine-driven and did not involve the braking system. Now let’s begin with the DOT 3 brake fluid. This type of fluid is one of the most common brake fluids used out there and it is worth noting that this type of fluid is mainly used on older vehicles that are not reached the DOT 4 standard. The DOT 3 is equivalent to the SAE J1703 standard.

The thing to note is that the dry boiling temperature is the temperature when we consider using DOT 3 from a new container. Meaning that this fluid is totally fresh. While the wet boiling temperatures are when this fluid is diluted with water. And what about the difference between DOT 3 and DOT 5 brake fluid? What is different between the two fluids and what are the pros and cons of each one?The advantages of mineral oil are that it tends to last longer and it’s not corrosive to your bike’s paintwork. That said, if any does manage to get onto a component or paintwork, you should still wipe it off with isopropyl alcohol and a rag.

The DOT 4 has a dry boiling temperature of 446 degrees Fahrenheit while the wet boiling temperature is 311 degrees Fahrenheit. This is a big improvement over the previous designs that have really poor performance on different temperatures and the DOT 4 can be used on heavy-duty applications. Since a lot of people are confused by the numbers and could easily go for a DOT 5 and ruin their braking system completely. So, what are the pros and cons of running DOT 5 in your car? Let’s elaborate on them in the following two chapters. Pros Due to its hydrophobic properties it has a very long life-span meaning low maintenance and fewer fluid changes. It is also kinder to paintwork unlike corrosive glycol-ether based DOT fluids. This water content finds its way into the brake fluid via microscopic pores in brake hoses, seals, joints and seams. As we've learnt, water mixed with DOT fluid has an adverse effect on the brake fluid by reducing its boiling temperature and therefore reducing its performance. This problem is less prevalent in domestic vehicles as they usually use DOT 4 or other glycol-based brake fluids but it’s relatively more common in vehicles using DOT 5.Therefore, it becomes less effective over time and starts overheating your brake system. This way, it can damage your vehicle’s brake system and that’s why it’s critical to change on time. The addition of moisture reduces the boiling point of the brake fluid and if you don’t change it in time, it’ll start corroding the rubber parts of your master cylinder and wheel cylinders. DOT 4 brake fluid absorbs moisture via the brake lines. As you keep pressing the brake pedal, the fluid in the system warms up. Source: Pixabay A DOT 5 brake fluid does not absorb moisture and does not affect painted surfaces, making it ideal for high-performance vehicles. Using this brake fluid protects the braking system from the effects of bad weather.

Glycol-based fluids consist of a mixture of ingredients with as many as ten separate substances making up the final product. These substances can be broken down into four key components: DOT 5.1 is totally different than DOT 5 brake fluid. Think of 5.1 as a glycol based DOT 4 fluid that meets DOT 5 silicone-based fluid standards. The 5.1 fluids are used primarily in vehicles equipped with ABS brake systems. Are you thinking of topping off the DOT 3 with the DOT 5 brake fluid? If this is the case, then you need to read this article first because the switch will not be that smooth after all and you could face a ton of issues. But since one is silicon-based and the other is glycol-based, these two brake fluids need to be distinguished. Hence the names DOT 5 and DOT 5.1. There are four types of braking fluid: DOT 3, DOT 4, DOT 5.1, and DOT 5. As kinetic energy is converted to heat by brakes, brake fluids are subjected to a fair degree of heating. Source:Apel USASilicone based fluid is more compressible than glycol based fluid, leading to brakes with a spongy feeling. [14] It can potentially suffer phase separation/water pooling and freezing/boiling in the system over time - the main reason single phase hygroscopic fluids are used. [ citation needed] Characteristics of common braking fluids [15] [14]

Brake fluids must not corrode the metals used inside components such as calipers, wheel cylinders, master cylinders and ABS control valves. They must also protect against corrosion as moisture enters the system. Additives (corrosion inhibitors) are added to the base fluid to accomplish this. Silicone is less corrosive to paintwork than glycol-ether based DOT fluids. [14] DOT 5 brake fluid (not to be confused with DOT 5.1) is fundamentally different than the rest of the DOT fluid range in that it is silicone based brake fluid. More precisely to use the good old glycol borate ester formula from the previous generations but to make it better and perform as the DOT 5 brake fluid.However, it can only handle a certain amount of heat before it begins to boil. During the boiling process, air bubbles will develop and compress the fluid, affecting the braking system’s performance. DOT 5 brake fluid is typically much more expensive than DOT3 or DOT4 brake fluid. It can cost up to five times as much as your standard brake fluid for a bottle. This price difference isn't huge, but it is a definite difference between the two types of fluid. What is good is that the DOT 4 is interchangeable when it comes to mixing with the DOT 3 since they are both glycol-based solutions. Having to choose a brake fluid is not as easy as you probably think because there are more than a few of them and this could be a big challenge for you as a car owner because choosing the right one will be a big headache in some cases. Brake fluid performance in extreme temperatures is the primary concern of the standards. As part of its criteria, they require that the fluid makers conform to a set of minimum boiling temperatures.