What Do DOT 3, DOT 4, and DOT 5 Brake Fluids Mean?

Apr 7 02:00 2022 Emily Sara Print This Article

Brake fluid is required for all types of vehicles. It makes no difference whether you're driving a car, a truck or a motorcycle. Look for full car service near me garage online and make sure your brake fluid service is completed according to the manufacturer's schedule.

The transmission of pressure from the brake lever to the brake pads is handled by braking fluids. These fluids must be non-compressible in order to effectively transfer force. The ideal brake fluid should have a high boiling point,Guest Posting be able to lubricate the calipers, and be corrosion resistant. There are four different types of brake fluid. DOT 3, DOT 4, DOT 5.1, and DOT 5 brake fluids are available. Since brakes convert kinetic energy to heat, brake fluids are exposed to an average amount of heat.

It can, however, only endure a limited amount of heat before boiling. When it boils, air bubbles develop, making it compressible, which has an impact on how the braking system functions. The most often utilised brake fluids in vehicles are DOT 3 and DOT 4. This comparison of DOT 3 vs. DOT 4 brake fluids will assist you in making the best choice for your vehicle.

The Definition of DOT Brake Fluid

The DOT fluid is the most widely utilised braking fluid nowadays. Except for the DOT 5 braking fluid, all DOT fluids have a poly-glycol basis. The final products of glycol-based braking fluids are made up of up to 10 different constituents. The substances may be divided down into four primary categories:

  • Inhibitors - These prevent oxidation and corrosion.
  • A Modifier-Coupler - This alters the quantity or strength of swells on exposed rubber portions.
  • A Solvent Diluent - The viscosity and boiling point of the braking fluid are determined by a solvent diluent. It makes between half to eighty percent of the braking fluid. A glycol ether is a regularly used solvent diluent.
  • A Lubricant - A lubricant, such as polypropylene or polythene, allows the pieces to move freely for 20% to 40% of the time.

The Department of Transportation and the Society of Automotive Engineers have set strict regulations and standards for DOT brake fluid. The Department of Transportation inspired the moniker DOT. The guidelines are focused on keeping brake fluids performing at both low and high temperatures. They also specify the minimum boiling temperatures to which the fluid's makers must adhere.

Complete a brake fluid service as recommended by the manufactures schedule by searching online for car service near me and booking your car in with a reputable garage.

DOT brake fluids come in a variety of varieties. DOT 5.1, DOT 5, DOT 4, DOT 3, and DOT 2 brake fluids are among the DOT brake fluid kinds. The boiling points or temperatures of the various classes of DOT brake fluids are what distinguishes them. Boiling points are the places in the braking system when the brake fluid begins to boil or evaporate. It is mostly caused by heavy and extended brake use, which has a negative impact on the entire braking system's performance.

What is DOT 3 Fluid and how does it work?

DOT 3 brake fluids are non-silicone, petroleum/non-mineral based, totally synthetic brake fluids that may be used in a variety of clutch and braking applications. It's manufactured by combining glycerin with alcohol. For great performance, the braking fluid is based on polyethylene glycol ether technology.

The key benefit of DOT 3 brake fluid is that it has high boiling temperatures, which ensures that it performs safely and consistently even when braking pressure is high. This braking fluid is intended to endure both high and low temperatures without boiling or thickening. High temperatures of up to 250° C may be tolerated by DOT 3 brake fluids.

In DOT 3 brake fluid, the rubber component swell is negligible, resulting in less fluid loss and leakage. It also provides great corrosion resistance, extending the life and dependability of the brake system's components.

This brake fluid may be used to top up or re-fill clutch and brake systems in heavy-duty trucks, motorbikes, 4WDs, and passenger vehicles. It's also suitable for agricultural, construction, and mining machinery.

When the vehicle manufacturer specifies DOT 3 brake fluid, use this brake fluid. Because the fluid is naturally hygroscopic, it collects water from the air, reducing the product's efficacy. To keep the brake fluid bottle from becoming contaminated with water, reseal the cap carefully after opening it.

The brake fluid should be changed according to the manufacturer's service guidelines. It is not recommended that DOT 3 brake fluid be mixed with Mineral or Silicone DOT 5. To avoid contact with paint, varnish, or skin, always use protective gear while applying brake fluid. If you come into touch with brake fluid on your skin, wash it with water right away.

What is DOT 4 Fluid and how does it work?

DOT 4 braking fluids are glycol ether-based with the addition of borate esters to boost performance. The wet and dry boiling points are two things that the borate esters enhance. In comparison to DOT 3, DOT 4 brake fluid has a higher and more stable boiling point. When it starts to absorb water, however, the boiling point drops faster than DOT 3 brake fluid.

According to the established criteria, DOT 4 should have a minimum wet boiling point of 155°C and a minimum dry boiling point of 230°. Only use the DOT 4 braking system if your brake system requires it or if the automobile manufacturer has stated it. This brake fluid is not recommended for use in lower or higher-grade vehicles.

It is advised that the DOT 4 braking system be replaced every two years to ensure the brake system's optimal safety and functionality. When water contaminates the braking system, its lifespan is reduced. Through the brake lines, DOT 4 brake fluid absorbs moisture. As you continue to operate the braking system, the brake fluid warms up.

As the braking fluids continue to absorb water from the air, their boiling point will drop. If you don't change your braking fluid on a regular basis, the rubber portions in your wheel cylinders and master cylinder will corrode. Because they are glycol-based, you may combine DOT 4 with DOT 3 and DOT 5.1 without affecting performance or causing harm to the brake system.

However, even if it is safe to mix them, we would not suggest you do so professionally. DOT 4 is a substitute for DOT 3, but not vice versa. Before you fill the reservoir with another type of brake fluid, be sure you've rinsed out all of the braking fluid from the system. This braking fluid is capable of withstanding temperatures of up to 311 degrees Fahrenheit. At 40 degrees Fahrenheit, DOT 4 has a viscosity of 1800.

What is DOT 5 Fluid and how does it work?

Most current vehicles utilise DOT 5 brake fluid, which is a silicon-based fluid. Because it has a high by-lining point, it is more costly than others. It boils at 356 degrees Fahrenheit when dry. Because the majority of modern brake rotors are thin and tiny, they disperse a lot of heat. Because it can endure high temperatures, this silicon-based brake fluid is suitable for this sort of vehicle.

DOT 5 brake fluid does not absorb moisture and is non-corrosive to painted surfaces. This brake fluid protects the braking system from the elements. DOT 5 can be used in lieu of DOT 3 and DOT 4 however, it should not be mixed with any other braking fluid. Bleeding silicon-based braking systems is more complicated.

A braking system loaded with DOT 5 brake fluid, on the other hand, will resist corrosion better and stay for longer after bleeding than other formulas. In freezing conditions, this braking fluid is also lighter. At 40 degrees Fahrenheit, it weighs roughly 900 grammes. In severe temperatures, the viscosity of DOT 5 is substantially more stable. It is suitable for use in most external boots and is compatible with all standard braking components.

DOT 5 brake fluids have significant disadvantages as well. When heated, it expands greatly, and the additives can evaporate at moderate temperatures, giving it a spongy sensation. Unless you flash it and replace the seal, this fluid is incompatible with systems that have previously employed glycol-based fluids. Because silicone fluids are more viscous, they are incompatible with anti-lock brakes. Unlike glycol brake fluids, which begin to compress as temperatures approach boiling, silicone brake fluids begin to compress when temperatures reach 300-350 degrees Fahrenheit.

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Emily Sara
Emily Sara

If you're still unsure, consult your owner's handbook or look up full car service near me garages online to chat with a technician who can recommend the correct brake fluid for your vehicle.

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