Types of Brake Fluid

Types of Brake Fluid
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Before we talk about the types of Brake Fluid, let’s first understand what a Brake fluid is. Brake fluid is a type of hydraulic fluid used in hydraulic brakes and hydraulic clutch applications in automobiles, motorcycles, light trucks and some bicycles. Without brake fluid, stopping your vehicle safely and instantaneously may be nearly impossible. It is used to transfer force into pressure, and to amplify braking force. It works because liquids are not easily compressible. Brake fluid is often made from glycol based liquids. Brake fluids must always meet International Standards Organizations ISO 4925 standards which defined classes 3, 4, and 5, as well as class 5.1 as performance categories. The difference between the four categories is in the wet and dry boiling points.

Let’s now talk about these categories in more detail:

DOT 3

This brake fluid is mainly glycol-based. This type of brake fluid has the lowest boiling point of all four.
● Dry boiling point: 205 °Ct
● Wet boiling Point: 140 °C
What you should know – DOT 3 is hydroscopic, which means it absorbs water and it requires replacing it at regular intervals every few years to maintain effectiveness.

DOT 4

Some of the European counterparts use mostly DOT 4 brake fluid. This is also a glycol-based with borate ester fluid and has a higher boiling point than DOT3. Most cars produced after 2006 use DOT 4 brake fluid.
● Dry boiling point: 230 °C
● Wet boiling Point: 155 °C
DOT 4 usually costs twice as much as DOT 3 to cover the cost of extra chemicals added. DOT 4 is witnessing significant growth in new markets and it is dominant in European and USA markets.

DOT 5

DOT 5 is a silicone-based fluid and it is immiscible with water, and other brake fluids. It must not be mixed with other types of brake fluid. Systems can change fluid only after a complete system flush. It has an advantage over other types of brake fluid in that silicone has a more stable viscosity index over a wider temperature range. It should be mentioned that DOT5 brake fluid does not damage paint. It has a significantly higher boiling point and it does not absorb water like other types of brake fluid.
● Dry boiling point: 260 °C
● Wet boiling Point: 180 °C

DOT5 brake fluid is not compatible with anti-lock braking systems.

DOT 5.1

DOT 5.1 is similar to DOT4 in that it is glycol based brake fluid but it has more additives and chemicals that give it a much higher boiling point than DOT 4 it is also called racing fluid. DOT 5.1 is basically a more advanced version of DOT 4 brake fluid.
● Dry Boiling Point: 270 °C
● Wet Boiling Point: 190 °C

Which one should you go for and how do you find the best Brake fluids?

You should always stick to equipment or vehicle manufacturer recommendation for the type of brake fluid to use. Using a DOT rating other than what is recommended may cause improper brake operation or premature failure.

Kuwait Dana Lubes is the manufacturer here in Kuwait for Shield lubricants we make top quality engine oils, industrial lubes, brake fluids, greases and all sorts of specialty lubricants.


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