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DOT 3 Vs. DOT 4 Vs DOT 5.1 Brake Fluid: Compatibility And Usage

Brake fluid is an essential component for successful braking systems. It performs the critical task of transferring pressure from the brake lever to the brake pads and must consequently be non-compressible. The ideal brake fluid will have a high boiling point and should also be able to lubricate calipers and resist corrosion.

Currently, four types of braking fluid are available in the market: DOT 3, DOT 4, DOT 5.1, and DOT 5. The type chosen by drivers depends on the style of their vehicle or racing performance specifications. As kinetic energy is converted to heat by brakes, a significant amount of heat is subjected upon the fluids, which requires them to handle more heat before reaching their boiling point.

Regarding viscosity, Dot 3 and 4 remain steady at temperatures up to 149°C (300°F). However, Dot 5 stands out with its larger transfer capability at 350°F (177°C). On the other hand, Dot 5.1 offers superior thermal stability compared to other fluids at 400°F (204°C).

Each braking fluid provides unique features for different driving applications, making it important for drivers to make a wise selection among them when making their choice. Read on to learn more in detail about it.

First, Let’s Get to Know Dot Fluid

DOT Brake Fluid is a special mixture containing various glycol-based components. It is the most widely used type of brake fluid, serving to lubricate and protect brake systems. Its unique formulation ensures safe, consistent operation in different working conditions.

The composition of DOT Brake Fluid consists of as many as 10 compounds divided into four primary groups – inhibitors, modifiers, couplers, and conditioners. Inhibitors help reduce oxidation and corrosion that could otherwise cause premature failure of essential brake parts. 

Modifiers cushion rubber components by preventing swelling when exposed to heat or moisture. Couplers maintain consistency under changing temperature conditions, while conditioners add lubrication to ensure smooth braking performance over long periods. This combination of ingredients produces a product that helps keep brakes free from mechanical breakdowns due to wear and tear or environmental conditions.

DOT 3

DOT 3 brake fluid is a petroleum/non-mineral based, non-silicone, totally synthetic brake fluid used in various clutch and braking applications. It is formulated with alcohol and glycerin and utilizes polyethylene glycol ether for its high-performance properties.

The boiling point of the brake fluid ranges from 205° C (dry) to 140° C (wet). This wide range guarantees a reliable and safe braking experience even at high temperatures and helps combat fluid boiling or thickening in hot or cold conditions.

DOT 3 fluids can conveniently handle temperatures much higher than normal braking environments – making them ideal brake fluids for vehicles subjected to extreme weather conditions or sustained heavy use.

Furthermore, proper maintenance, such as changing the full fluid after two years or 30,000 miles, should be followed to ensure optimal results. Always check your vehicle’s manual to determine what type of DOT rating you should use in different parts of the vehicle system.

DOT 4

DOT 4 brake fluid is a glycol ether-based and borate ester-boosted system that offers superior wet and dry boiling points than its predecessor, DOT 3. Most vehicles now have DOT 4 installed in their systems by default, as the long-term performance benefits of these fluids are far better. For example, the dry boiling point on this type of brake fluid is set at 230°C while the wet boiling point is 155°C.

This means it has greater resistance to overheating after extensive use and when submerged underwater; however, the extent of this benefit may vary in certain cases, so it’s advisable to consult the automobile manufacturer before inserting DOT 4 in your vehicle’s braking system. Additionally, not every bike or car requires DOT 4 brake fluid to work properly, so it is best to check before using this type of fluid.

DOT 5

DOT 5 brake fluid is becoming increasingly popular in the automotive industry due to its superior high boiling points. This feature makes it more costly than other options, but motorists willing to invest the money will be met with greater safety and performance benefits.

It boils at 260° C dry and 180° C wet, which should provide ample protection under most circumstances. The fact that DOT 5 does not mix with water also means that drivers do not need to worry about corrosion as much when using this type of fluid for their vehicle’s brakes.

Modern vehicles’ thin, compact rotors benefit from using DOT 5 since the silicon-based fluid can better handle the higher temperatures resulting from good heat dissipation.

In addition, the braking response should remain consistent even when on extended drives or under harsh conditions. Regardless, drivers should check their brakes regularly and stick within their vehicle’s specified brake fluid maintenance intervals to ensure they stay safe while on the road.

DOT 5.1

DOT 5.1 is a unique brake fluid that has gained popularity due to its superior performance compared to other DOT fluids and its ability to withstand higher temperatures without becoming sticky.

It combines a borate ester and polyethylene glycol ether and performs better than any other DOT brake fluid on the market. It has an impressive dry boiling temperature of 270° C and 190° C wet, making it one of the best options for vehicles requiring great braking capabilities.

Another advantage of using this type of brake fluid is its compatibility with all glycol-based fluids. While this does not include DOT 5, because it is silicone-based, there is no need to worry about mixing different brakes when working on your vehicle.

Dot 5.1 also offers excellent longevity, meaning you don’t have to replace it often to maintain optimal braking performance. Because of this, many drivers opt for this type of fluid as they know they can count on its reliability over time.

DOT 3 vs. DOT 4 vs DOT 5.1 Brake Fluid: Compatibility and Usage

DOT 3, DOT 4, and DOT 5.1 are the three most common types of brake fluid used in automobiles today. Each type is different from the others in terms of compatibility and usage.

DOT 3 brake fluid is a polyglycerol-based fluid with a glycol base with an added polymeric component. It has a low boiling point and is considered the least resistant of all brake fluids, making it suitable for older vehicles. The dry boiling point for this type of fluid is 205°C, and its wet boiling point is 140°C, which means it can easily boil over under extreme conditions.

DOT 4 brake fluid is a glycol ether-based and borate ester-boosted system that offers superior wet and dry boiling points compared to DOT 3. Its dry boiling point is 230°C, and its wet boiling point is 155°C.

This means it has greater resistance to overheating after extensive use and when submerged underwater; however, the extent of this benefit may vary in certain cases, so it’s advisable to consult the automobile manufacturer before inserting DOT 4 in your vehicle’s braking system.

DOT 5.1 is the latest advancement in brake fluid technology and is among the most efficient compared to DOT 3, 4, and 5. This high-boiling point fluid is a hybrid system that combines borate ester and polyethylene glycol ether. It has an impressive dry boiling temperature of 270°C and 190°C wet, making it a great choice for vehicles requiring superior braking performance.

When choosing the right brake fluid for your vehicle, it’s important to consider the boiling point, compatibility with other brake fluids, and cost. DOT 3 is the least expensive but not as effective as DOT 4 and 5.1; however, depending on your needs, it may be the best option for you.

Is it Safe to Mix Dot 3 and Dot 4 Brake Fluid?

Mixing Dot 3 and Dot 4 brake fluids is possible, as both glycol-based brake fluids are chemically compatible. While technically, any combination can be used in vehicles that require either one; it’s recommended to follow the manufacturer’s suggestion for brake fluid type when refilling or topping up your car.

For example, if your car has Dot 4 from the factory, refilling it with a mix of the two variants is not recommended. On the other hand, if you have been using Dot 3 from the factory, you may consider topping up with more than Dot 3 if you know that you often drive in steep terrain or pull trailers – switching to a mixture of both might be beneficial in such cases.

Is It Safe to Mix Dot 5 with Dot 3 and Dot 4?

Dot5 brake fluid is a silicone-based brake fluid that does not absorb water from the air and is incompatible with ABS systems. It has a higher boiling point than the existing brake fluids Dot3 and Dot4, making it more suitable for drivers with more aggressive driving styles. This also makes it desirable for customers looking for superior brake fluid to handle intense conditions better.

However, Dot5 should never be mixed with the other two Dot3 or Dot4 liquids, as compatibility will not be ensured. Before mixing any of these brake liquids, following the manufacturer’s recommendations and seeing if your braking system is even compatible with Dot5 to achieve optimal results is important.

Frequently Asked Questions [FAQs]

Conclusion

DOT 3, 4, and 5.1 brake fluids are chemically different and should never be mixed. While DOT 3 and 4 are compatible with each other, they should still be used in accordance with the manufacturer’s recommendation. Finally, DOT 5.1 is incompatible with ABS systems and should not be used when an ABS-equipped vehicle is present. It offers superior performance in extreme conditions but must not be mixed with other types of brake fluids.