Difference between

Dot 3 & dDot 5 Brake Fluid

What is Brake Fluid?

Before taking a deep dive into the different types of brake fluids, first, we need to learn what brake fluid is and how it works. A vehicle’s braking system rapidly converts kinetic energy into heat in order to reduce the car’s momentum. In today’s world, brake fluids are used to build up the pressure a braking system requires to make those brake pads and rotors work.

Why is Brake Fluid Important?

Firstly, it is important for perfect braking performance, in fact, having the right braking fluid for your car would minimize the risk of accidents (Learn in detail here why your car shakes when braking). A DOT rating represents that the product has met or exceeded the Federal Motor Carrier Safety Administration’s (FMCSA) safety fitness standards. A DOT rating can be broken down into 3 properties; boiling point, chemical substance and moisture control over time.

Types of Brake Fluids

Typically, three types of brake fluids are available in the market; DOT3, DOT4 and DOT5. If you are new to driving, you must be thinking about what these numbers suggest? DOT3 represents the basic type of brake fluid, while DOT5 is considered the premium one. DOT4 has recently started gaining popularity and is being used in regular vehicles. Before that, DOT3 saved the spot.

DOT3 Brake Fluid

Like we said earlier, DOT3 is the basic one. The quality of the brake fluid improves as the number ascends. It comprises 80% Glycol and 20% other substances. It comes in blue color. The boiling point for different DOT3 brake system fluids varies from brand to brand. However, generally, they have 140 degrees Celsius wet boiling point and 205 degrees Celsius dry boiling point

DOT4 Brake Fluid

DOT4 has recently got popular due to its outstanding properties. It is being more commonly used as it closes the gap between DOT3 and DOT5. It boasts the properties of both and comes at affordable prices. This is one of the reasons why it is popular across the US. If we talk about its composition, it comprises 50-65% Glycol ether base and 20-40% Borate Ester base. Its wet boiling point is 170 degrees Celsius and 270 degrees Celsius dry boiling point.

DOT5 Brake Fluid

DOT5 is a high-end brake fluid used in most vehicles made for high-intensity conditions. Since it comprises silicone, it is less likely to contain moisture with time. With 180 degrees Celsius wet and 260 degrees Celsius dry boiling point, the fluid offers more compressibility and reliability than the other two types. If you wish to achieve stupendous braking performance and have a flexible budget, you should definitely go for DOT5.

Comparison of

DOT3 Brake Fluid

DOT5 brake fluid

Dry: 401 F/205 C Wet: 284 F/140 C

It comprises ether and Polyalkylene glycol

Its dry and wet boiling capacity is better than DOT4

New ones are bluish in color

Dry: 500 F/260 C Wet: 356 F/180 C

It is made of blended hydrophobic Polydimethylsiloxane and Tributyl phosphate.

It has the best dry and wet boiling capacity.

It is purple in color











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