The brake liquid is perhaps the most important fluid in your vehicle. If the level of brake fluid is too low or has already lost its properties it can put both your safety and that of the passengers at serious risk.
With that said, how can you tell if the brake fluid has already lost its properties and therefore your vehicle requires a brake fluid change? Moreover, in case you need to service your brake system, what would be the right brake fluid to use? DOT 3, DOT 4, DOT 5.1?
In this article, we will answer these and other key questions concerning this important topic.
At a Glance: Our Top Picks for Brake Fluid
- OUR TOP PICK: Pentosin DOT4 LV Brake Fluid
- RUNNER-UP: ATE Original TYP 200 Racing Quality DOT4 Brake Fluid
- BEST BUDGET OPTION: Prestone DOT4 Synthetic Brake Fluid
Comparison of the Best Brake Fluids
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Is All Brake Fluid The Same?
No, all brake fluids are not the same. In fact, there are significant differences regarding their properties, their useful life, and the type of application for which they are recommended. It should be noted, that the correct type of brake fluid to use in your vehicle will be written on your brake fluid resevoir cap and also in the service manual.
Below, we analyze the main types of brake fluid, namely:
DOT 3
It is the most common type of brake fluid, ideal for pre-2010 daily driving vehicles. It has the lowest boiling points, 205 °C (401 °F) dry boiling point and 140 °C (284 °F) wet boiling point.
DOT 4
Similar in composition to DOT 3 but with additives that enhance its properties to reach 230 °C (446 °F) dry boiling point and 155 °C (311 °F) wet boiling point. This fluid is designed for applications that require more robust brake systems such as modem passenger cars, trucks, and full-size SUVs. A disadvantage of this liquid is that it absorbs water more quickly, so it has to be replaced more frequently than DOT 3 fluid.
Super DOT 4
Exceeds the properties required by the DOT 4 standard, hence its name. It can reach dry boiling points over 340 °C (644 °F) which makes it ideal for racing applications and high-performance vehicles. Moreover, in many cases, this fluid also has enhanced hygroscopic properties which makes it less prone to absorb water.
DOT 5.1
It is in many ways similar to DOT 3 and DOT 4 fluids, but its formula allows it to have the same minimum wet and dry boiling points as DOT 5. Additionally, this type of liquid is less viscous which is required by the ABS and ESC systems of newer vehicles.
DOT 5
Even though its notation suggests that it is a less advanced brake fluid than DOT 5.1, the reality is quite the opposite. This type of brake fluid is silicone-based and does not absorb moisture like DOT 3, 4, or 5.1 fluids. It is extremely expensive and should only be used on vehicles that explicitly specify it.
Buying Brake Fluid: What to Look For
Choosing the best brake fluid depends on several aspects. Let's review some of them.
Hygroscopic Properties
Have to do with the ability of the brake fluid to absorb water. In the case of DOT 3, 4, and 5.1 brake fluids, their hygroscopic properties largely determine their service interval as it affects the fluid’s compressibility.
Compressibility
Under normal conditions, all liquids have low compressibility which allows them to transfer energy in hydraulic systems. However, as brake fluid absorbs moisture its properties change. Since water has a lower boiling point than brake fluid, it can easily boil, creating bubbles in the system.
Unlike liquids, vapors are compressible, so these bubbles can dramatically increase the compressibility of the fluid, making it less effective. Hence the importance of the hygroscopic properties of brake fluid.
Viscosity
In very cold environments or vehicles with the latest generation ABS and ESP systems, the viscosity becomes a determining factor. That’s why most manufacturers require brake fluids with low viscosity levels.
Dry Boiling Point
This is one of the most important factors to consider. The “dry” boiling point is the temperature at which the fluid boils when it is in a pure state (without moisture). The higher the boiling point, the better the fluid's ability to withstand the high temperatures generated by the brake system.
Wet Boiling Point
It is the boiling point when the brake fluid has a water content of approximately 4% by volume. Like the dry boiling point, the higher it is, the more beneficial for the brake system. The wet boiling point gives you an idea of how often you should change the fluid (the lower the boiling point, the more often you should change it).
Review of the Best Brake Fluids
Ready to explore the best brake fluids on the market? In this section, we will review each of the types of brake fluid available, as well as their most common applications.
PROS
CONS
What Are This Fluids Specs?
- Exceeds DOT 4 boiling point specifications of 230 °C dry and 155 °C wet
- Color: clear/yellow
- 265 °C (509 °F) dry boiling point (+35 °C)
- 170 °C (338 °F) wet boiling point (+15 °C)
- 6.4 mm2/s kinematic viscosity at 40 °C
- Meets FMVSS 116 DOT 4, ISO 4925 Class 6, SAE J1704 specifications
- Available in 1 liter and 5-liter bottles
What Type of Driver is This Fluid Best For?
Its low viscosity, excellent resistance to moisture absorption, and protection against corrosion make Pentosin DOT 4 LV brake fluid ideal for newer passenger cars and SUVs equipped with advanced ABS, ASR, and ESP systems. Its high boiling points also allow Pentosin DOT 4 LV to be used for occasional spirited driving.
Should I Choose a Different Option in this List?
Despite its exceptional qualities, Pentosin DOT 4 LV brake fluid is not the best choice for all vehicles, especially those before 2010. In vehicles equipped with older ABS systems, the low viscosity of Pentosin DOT 4 LV can give the pedal an unpleasant feeling of smoothness that can even impair your ride. For that kind of vehicle, it is better to use DOT 3 brake fluid. Your brake fluid cap should specify the type to use.
Bottom Line
Pentosin DOT 4 LV Brake Fluid is undoubtedly a solid choice for newer daily driving vehicles. Its impressive formulation will protect the brake system from corrosion and keep it properly lubricated. Moreover, its excellent hygroscopic properties give it a service life similar to DOT 3 fluids. However, if you plan to replace the brake fluid and your vehicle is older than 2010, we strongly recommend that you continue to use DOT 3 brake fluid or whatever the manual dictates.
PROS
CONS
What Are This Fluids Specs?
- Exceeds DOT 4 boiling point specifications of 230 °C dry and 155 °C wet
- Color: yellow
- 280 °C (536 °F) dry boiling point (+50 °C)
- 198 °C (388 °F) wet boiling point (+43 °C)
- Viscosity at +100 °C/212 °F 2.2 to 2.8 mm²/s
- Exceeds FMVSS 116 DOT 4, ISO 4925 Class 4, SAE J1704 specifications
- Available in 1-liter can
What Type of Driver is This Fluid Best For?
ATE DOT 4 TYP 200 Brake Fluid is hands down one of the best products you can use in spirited driving and high-performance vehicles. Moreover, its extraordinarily high boiling points make this fluid an ideal candidate for applications requiring heavy braking since it can withstand the high temperatures generated by brake pads friction. Such applications include towing/hauling, extreme off-roading, and more.
Should I Choose a Different Option in this List?
Two factors make ATE DOT 4 TYP 200 brake fluid a niche product. Its high price and its outstanding properties. The brake system of most vehicles does not generate enough temperature to take advantage of the properties of ATE DOT 4 TYP 200 brake fluid. For this reason, we only recommend this fluid for competition vehicles and very specific applications that require constant braking. For normal driving, it is a better option to use regular DOT 3 or DOT 4 fluids.
Bottom Line
If you are preparing for a competition and your vehicle has a race-grade braking system, ATE DOT 4 TYP 200 blake fluid will not disappoint. Its unique formula will guarantee your safety throughout the event. However, daily driving vehicles are likely to benefit the most by using brake fluids more tailored to their specific needs.
PROS
CONS
What Are This Fluids Specs?
- Meets or exceeds DOT 4 boiling point specifications of 230 °C dry and 155 °C wet
- Color: yellow/clear
- 266 °C (510 °F) dry boiling point (+36 °C)
- 155 °C (311 °F) wet boiling point (+0 °C)
- Complies with FMVSS 116 DOT 4, meets SAE J1704 and J1704 specifications
- Available in 12 oz and 32 oz bottles
What Type of Driver is This Fluid Best For?
The Prestone DOT 4 Synthetic Hi-Temp Brake Fluid is a solid candidate for daily driving vehicles. Its chemical properties are slightly better than those required by the DOT 4 standard, it's inexpensive, and it also offers additives that help protect the brake system from corrosion. Another added benefit is its compatibility with almost all types of ABS systems (more on that shortly).
Should I Choose a Different Option in this List?
The Prestone DOT 4 Synthetic Hi-Temp Brake Fluid is probably the best choice for 80% of daily driving vehicles. Nevertheless, in the case of newer vehicles using advanced ABS, ESP, and ASR systems the car manufacturer might force you to use specialized brake fluids such as the Pentosin DOT 4 LV reviewed above.
Bottom Line
Overall, the Prestone synthetic DOT 4 is a good brake fluid offering an excellent balance between price and properties. As said, in most cases it could be the ideal solution for daily driving cars, trucks, and SUVs. However, if you own a last-gen vehicle (especially a luxury one) it is better to double-check the owner's manual before opting for this product.
PROS
CONS
What Are This Fluids Specs?
- Exceeds DOT 5.1 boiling point specifications of 260 °C dry and 180 °C wet
- Color: Yellow
- 269 °C (516 °F) dry boiling point (+9 °C)
- 187 °C (369 °F) wet boiling point (+7 °C)
- Viscosity at +100 °C (212 °F) 2.1 mm²/s
- Exceeds FMVSS 116 DOT 5.1 non-silicone base, ISO 4925 (5.1, 4, 3), SAE J1703 specifications
- Available in 500 ml bottles
What Type of Driver is This Fluid Best For?
If your vehicle manufacturer recommends the use of DOT 5.1 brake fluid then Motul may have the solution for you. The Motul DOT 5.1 Brake Fluid has all the elements to be considered a good option for daily driving vehicles. Excellent price, advanced anti-corrosion formulation, high boiling points, and low viscosity that favors the most modern ABS systems.
Should I Choose a Different Option in this List?
Assuming your car or truck uses DOT 5.1 fluid, we can only imagine a few cases where we would not recommend using this particular brake fluid. We refer to high-performance sports cars that require higher boiling points, or very heavy vehicles that need superior braking capacity in adverse conditions. In that case, we advise you to check the Ravenol DOT 5.1 brake fluid at the end of this list.
Bottom Line
Motul fully synthetic DOT 5.1 brake fluid is hands down an excellent choice for car owners looking for a quality product that ensures reliable brake performance. It's a good option for daily driving vehicles ranging from luxury sedans to full-size SUVs to compacts. Its low viscosity also makes this fluid ideal for newer vehicles with sophisticated ABS systems. Perhaps the only use case where you may want to consider a different option is high-performance applications.
PROS
CONS
What Are This Fluids Specs?
- Meets or exceeds DOT 3 boiling point specifications of 205 °C dry and 140 °C wet
- Color: clear/yellow
- 238 °C (460 °F) dry boiling point (+33 °C)
- 140 °C (284 °F) wet boiling point (+0 °C)
- Meets or exceeds FMVSS 116 DOT 3, SAE J1703 specifications
- Available in 12 oz bottles, 32 oz bottles, and 1-gallon bottles
What Type of Driver is This Fluid Best For?
Prestone DOT 3 Synthetic Hi-Temp Brake Fluid is a very particular product. In an era where DOT 3 fluids are being superseded by DOT 4 and DOT 5.1 specifications, this product offers compelling advantages. Its low price and high boiling point make it an option to consider in pre-2010 daily driving vehicles.
Should I Choose a Different Option in this List?
Depending on the year of your car and the type of ABS system it has installed, it may be a good idea to consider another type of fluid such as the Prestone DOT4 Synthetic Brake Fluid which offers better features all around. While it is true that DOT 4 fluid requires more frequent changes, it is also true that we are talking about services that are done every 12-18 months compared to the 24-month service intervals that DOT 3 offers.
Bottom Line
Prestone DOT 3 brake fluid is a good alternative if you prefer to keep your vehicle with the same type of fluid that it came with from the factory. However, if you want to improve the performance of your vehicle under severe braking conditions, a fairly simple option would be to change the fluid and start using DOT 4 brake liquid.
PROS
CONS
What Are This Fluids Specs?
- Exceeds DOT 4 boiling point specifications of 230 °C dry and 155 °C wet
- Color: clear/yellow
- 265 °C (509 °F) dry boiling point (+35 °C)
- 165 °C (329 °F) wet boiling point (+10 °C)
- 7.9 mm2/s kinematic viscosity at 40 °C
- Exceeds FMVSS 116 DOT 4, ISO 4925 Class 4, and SAE J1704 specifications
- Available in 0.25 liter, 0.5 liters, 1 liter, and 5-liter bottles
What Type of Driver is This Fluid Best For?
If you are looking for noticeably better brake fluid than regular DOT 4, then the Pentosin Super Dot 4 will not disappoint. Its exceptional hygroscopic properties and high boiling points ensure that you don't have to worry about air bubbles in your brake system. It is for this reason that the Pentosin Super Dot 4 is a valid alternative for owners of luxury vehicles and even sports vehicles.
Should I Choose a Different Option in this List?
Although it offers excellent specs, Pentosin Super Dot 4 may not be the right brake fluid for your vehicle. Some modern vehicles require the expensive DOT 4 LV fluid (such as the Pentosin LV reviewed at the beginning of this list) which has an ultra-low viscosity level. It is for this reason that we advise you to check your car owner's manual before making a decision.
Bottom Line
Generally speaking, Pentosin Super Dot 4 brake fluid provides a considerable improvement over the DOT 4 standard. This product could be the ideal choice for sports or luxury vehicles that do not require an ultra-low viscosity brake fluid for the proper operation of the braking system.
PROS
CONS
What Are This Fluids Specs?
- Exceeds all street brake fluid specifications (Super DOT 4, DOT 5)
- 335 °C (635 °F) dry boiling point (+25 °C over conventional LCF 600 plus high temp racing fluid)
- Exceeds conventional racing fluid specifications by a wide margin
- Available in 500 ml bottle
What Type of Driver is This Fluid Best For?
As you can guess from looking at its specifications, Brembo HTC 64T fluid is specifically designed for professional use in race cars. In fact, this product cannot be used legally on the street. All in all, this Brembo product is possibly one of the best (if not the best) racing brake fluid currently available on the market.
Should I Choose a Different Option in this List?
You should not attempt to use this product in your vehicle unless it is a race car with a brake system prepared to use this type of brake fluid. If all you need is a premium product for fun on the track or even mild racing, then we suggest the ATE Original TYP 200 Racing Quality DOT4 Brake Fluid.
Bottom Line
If what you need is a state-of-the-art brake fluid used in Formula One vehicles, then the Brembo HTC 64T will not disappoint. This fluid guarantees maximum performance at any imaginable temperature. However, for more moderate racing applications we suggest using a Super DOT 4 brake fluid, which is considerably cheaper and can also be used on the street.
PROS
CONS
What Are This Fluids Specs?
- Exceeds or meets DOT 5 boiling point specifications of 260 °C dry and 180 °C wet
- 300 °C (572 °F) dry boiling point (+40 °C)
- 180 °C (356 °F) wet boiling point (+0 °C)
- Viscosity at +100 °C (212 °F) 5.8 mm²/s
- Exceeds or meets FMVSS 116 DOT 5 specifications
- Available in 250 ml bottles (6-pack)
What Type of Driver is This Fluid Best For?
While it is true that DOT 4 and Super DOT 4 brake fluids are more flexible and offer better boiling points than DOT 5 fluids, it is also true that their hygroscopic properties will always create problems. Products like EBC Brakes DOT5 Silicone Brake Fluid eliminate these problems. Thanks to its unique formulation, DOT 5 brake fluids do not absorb moisture, which makes them ideal for vehicles that remain parked for prolonged periods such as military and industrial applications, as well as classic and collector vehicles that are rarely driven.
Should I Choose a Different Option in this List?
Despite its advantages, you should be aware that DOT 5 brake fluid also has its limitations. The most notable is that it cannot be mixed with DOT 3, DOT 4, or DOT 5.1 liquids. If you also take into account its high price, you will realize that it is a type of fluid that offers very little value. Our recommendation is to only use it if your vehicle requires it, or in special cases (such as classic cars) where its cost is justified.
Bottom Line
EBC Brakes DOT5 Brake Fluid allows for fairly long service intervals (as it does not absorb water), is inert (will not damage your car's paint), and has high boiling points. These characteristics make it ideal for vintage cars that spend most of their time unused. However, unless your car manufacturer recommends this type of fluid, you will benefit more by using a DOT 4, DOT 4 LV, or Super DOT 4 brake fluid such as those discussed in this article.
PROS
CONS
What Are This Fluids Specs?
- Exceeds or meets DOT 5.1 boiling point specifications of 260 °C dry and 180 °C wet
- Color: light yellow
- 280 °C (536 °F) dry boiling point (+20 °C)
- 180 °C (356 °F) wet boiling point (+0 °C)
- Viscosity at +100 °C (212 °F) 2.16 mm²/s
- Exceeds FMVSS 116 DOT 5.1 non-silicone base, ISO 4925 (5.1, 4, 3), SAE J1703 specifications
- Available in 1-liter can
What Type of Driver is This Fluid Best For?
The Ravenol DOT 5.1 brake fluid is undoubtedly a solid alternative to the Motul DOT 5.1 that we have already reviewed. While Motul has the advantage of offering a higher wet boiling point, Ravenol DOT 5.1 brake fluid outperforms it with an impressive dry boiling point of 280 °C. These properties make Ravenol DOT 5.1 fluid not only ideal for everyday driving but also for spirited driving and occasional track days.
Should I Choose a Different Option in this List?
Ravenol DOT 5.1's high boiling point gives it exceptional performance as long as the fluid is free of moisture. However, as time passes, their properties inevitably decrease. In that sense, Motul DOT 5.1 brake fluid has the advantage of maintaining its chemical properties for a longer period. Moreover, Motul fluid is considerably cheaper than Ravenol, which makes it a better option for daily driving vehicles.
Bottom Line
Hands down, the Ravenol DOT 5.1 Synthetic Brake Fluid is an excellent choice for any type of vehicle No matter if you own a passenger car, truck, or SUV Ravenol will provide dependable braking performance regardless of your driving style. Yet, there are other alternatives, such as the Motul DOT 5.1, that provide similar results at a fraction of its price.
How Often Should Brake Fluid Be Changed?
The hygroscopic properties of brake fluid cause it to absorb moisture from the air and degrade over time. It is for this reason that changing it on time is essential to avoid losing its properties. Here are some general guidelines about how often you should change your brake fluid depending on your vehicle usage.
- Daily driver. Under normal conditions, most fluid manufacturers suggest changing the brake fluid every 2 years. For daily driver vehicles, we suggest using DOT 4 or DOT 5.1 brake fluids as they have a higher boiling point. However, keep in mind that if your fluid color turns dark, it would be a good idea to reduce this interval to 12-18 months (especially if it is DOT 4 or DOT 5.1).
- Spirited driving / occasional track usage. For more aggressive driving styles we recommend using performance-oriented brake fluids such as those described in this guide. For this type of vehicle, it is advisable to change all the fluid every 6-12 months or sooner if its color turns dark.
- Racing usage. For racing vehicles, we suggest using high-end products such as the Brembo HTC 64T or the ATE Original TYP 200. In this type of application, it is not uncommon to change the brake fluid every race (along with the brake discs and pads), if necessary.
Cautious Considerations to Keep in Mind
Before buying brake fluid for your vehicle, consider the following factors:
- Regardless of its type (DOT 3, DOT 4, DOT 5, DOT 5.1) or the brand you buy, brake fluid is extremely toxic. Avoid contact with skin and eyes and keep it out of the reach of children and pets.
- With the exception of DOT 5, all brake fluids are caustic in nature, so they have the potential to destroy your vehicle paint job. Handle brake fluid with extreme care when pouring it into the master cylinder container and always have a microfiber cloth at hand to clean up any spills immediately.
- Once the bottle is opened, the brake fluid begins to degrade (begins to absorb moisture from the environment). That is why we recommend only buying the fluid you are going to use. If for any reason you have to store it, do so without opening the bottle.
- Before buying brake fluid, read your owner's manual carefully to find out what type of fluid your vehicle uses. If your manufacturer recommends DOT 3 or DOT 4 brake fluid you have the option of purchasing DOT 5.1 fluid as they are fully compatible. On the other hand, if your car uses DOT 4 you can only use DOT 4 or DOT 5.1 brake fluid. Finally, use caution if your vehicle is using DOT 5 as you can only use the same type of brake fluid.
Brake Fluid Change / Brake Fluid Flush Cost
Changing the brake fluid normally costs between $70 to $110 regardless of the type of vehicle. Most of this cost is labor, as the process is quite time-consuming. This price may vary slightly if you use a DOT 5 brake fluid as its cost is higher.
Brake Fluid Color: What Color is Brake Fluid?
Brake fluid usually has a color similar to that of light beer. Some brands even use a transparent color. The reason behind this light color more than aesthetics is practical. As the brake fluid absorbs water and loses its properties, it becomes darker, like if it was corroded. Once it contains enough water it even accumulates rust particles. So if you notice a dark color in the brake fluid container then it is time to plan a complete system flush. Refer to the section "How To Flush Brake Fluid" for more information on how to proceed in this case.
DOT 3 vs DOT 4 Brake Fluid
From a chemical point of view, DOT 3 brake fluid is almost completely based on glycol ether whereas the DOT 4 brake fluid adds borate esters to enhance its properties, most notably, its boiling point. That property, the boiling point, is precisely the major distinction between the two fluids.
The DOT 3 standard requires a minimum dry boiling point of 400 degrees Fahrenheit, however, the DOT 4 standard demands a minimum dry boiling point of 450 degrees Fahrenheit along with more stringent hygroscopic properties.
DOT 5 vs 5.1 Brake Fluid
DOT 5 brake fluids use an advanced silicone-based formulation to meet the stringent viscosity properties and high boiling points of the DOT 5 standard. This formulation is generally used in applications such as military vehicles, race cars, and classic cars.
On the other hand, DOT 5.1 brake fluids are easier to produce since they use a formula based on glycol ether and borate esters. This formula in many ways is similar to that used by DOT 4 and DOT 3 fluids which makes the DOT 5.1 compatible with them even when it meets the standards of the DOT 5 classification. Simply put, silicone-based DOT 5 fluid should not be mixed with any other brake fluid whereas the DOT 5.1 brake fluid could be safely used along with DOT 4 and even DOT 3 fluids since they share a similar formula.
How to Flush Brake Fluid
Below we will outline the main steps to flush the brake fluid from your car. However, for your convenience, we also include a video at the end of this section that shows you the step-by-step procedure on how to do it.
1. Have everything you need at hand. Consult your vehicle's service manual for the type of brake fluid your car uses as well as the approximate amount you will need. You will also need a suitable line wrench, a reservoir for the old fluid, a turkey baster, rags or towels, and a hose that fits the bleed valve. Also, you will need a friend to help you through the brake fluid bleeding process.
2. Prepare the vehicle. Raise your vehicle and secure it by placing a jack on each of the manufacturer's recommended support points.
3. Empty the master cylinder reservoir. Clean the master cylinder and reservoir cap to prevent dirt from entering the brake system. Next, remove the cap from the master cylinder reservoir and, using the turkey baster, remove as much of the brake fluid as you can without letting air entering into the system.
4. Fill the reservoir with new brake fluid. Now slowly pour new brake fluid into the reservoir until it reaches the "MAX" level.
5. Flush the old brake fluid. Starting with the wheel furthest from the master cylinder (usually the rear passenger-side wheel), connect the hose to the brake bleeder screw, secure it so fluid does not leak, and then prepare to open the bleeder with the wrench. line. With the help of an assistant, tell the person to apply the brakes (and keep them on) until the ok signal is given. Once the brake pedal is applied, you can open the bleeder valve to allow fluid to flow through the hose to the waste container. Close the bleed valve and tell your assistant to release the brake pedal. Repeat the procedure until you notice the color of the liquid changes from dark to light.
6. Keep an eye on the master cylinder. During the procedure, it is crucial to check the fluid level in the master cylinder reservoir at all times. Complete as necessary to prevent air from entering the system.
7. Repeat the bleed procedure on the other wheels. After the first wheel is finished, lock the bleed valve, and repeat the bleed procedure on the second wheel furthest from the master cylinder. When finished, go to the third and finally the furthest fourth wheel.
Conclusion
Choosing the right brake fluid for your vehicle is an important decision. Regardless of the type of application, you put your safety and the safety of the passengers in the hands of every single component of the brake system, and that includes brake fluid.
In this review, we have looked at all types of brake fluid, from DOT 3 to DOT 5.1 and even specialty racing fluids. When choosing the one that best suits your needs, we advise you to carefully review the key points that we have discussed in this article. The ability to absorb moisture, boiling points, viscosity, and compatibility with modern ABS systems. Finally, no matter what, always consult your owner's manual before making a final decision.
People Also Ask
Still, have questions about brake fluids? Do not worry. In this section, we answer the most common questions regarding this topic.
How to Add Brake Fluid?
You only need to add brake fluid if it is below the "MIN" line. If that is the case, first carefully wipe the reservoir with a clean cloth. Check your owner's manual for the correct type of fluid for your car (DOT 3, 4, 5.1, or 5). Carefully remove the reservoir cap and then pour brake fluid up to the "MAX" mark. Do not exceed this limit as it may cause spills. Put the reservoir cap again and clean any excess fluid.
What Does Brake Fluid Do?
Since your car's brakes are based on a hydraulic system, they require fluid to function. That special liquid is the brake fluid. The brake fluid is responsible for transmitting the energy that you apply in the brake pedal to each of the calipers and cylinders of the brake system.
How to Dispose of Brake Fluid?
The brake fluid extracted from your car is considered a dangerous liquid as it is highly flammable. Besides, once it has been in service it absorbs huge amounts of metals so it is also toxic and dangerous if consumed by humans or animals.
To dispose of small quantities, you can empty it into a container with kitty litter and wait for it to evaporate completely (3 or 4 days) before throwing it away in a closed bag. In case you need to dispose of large quantities of brake fluid (more than one liter) a better option is to take it to a toxic waste treatment center.
How Much Brake Fluid to Flush?
Whether you just need to bleed the front brakes, the rear brakes, or all of them, a 500 ml bottle should be sufficient. However, if you notice that the brake fluid is dark in color then it would be a good idea to flush out all the old fluid in which case you will need more than one bottle. Consult your car's service manual for more information on the exact amount if that is the case.
How Long Does Brake Fluid Last?
Brake fluid can last up to two years in its container if it has not been opened. Once the container is opened, the brake fluid begins to absorb moisture immediately, so it is advisable to keep it sealed until it is used. For this same reason, it is recommended to change your brake fluid every two years (at a minimum) as part of your preventive maintenance.
What Does Brake Fluid Smell Like?
Since brake fluid is usually clear or yellow when there is a leak its distinctive fishy smell is often noticed first before actually seeing the leak. Once you detect a leak you can tell that it is brake fluid not only by its fishy/castor oil smell but also because it is oily, even a little sticky when it is old.
What Do I Do if I Have No Brake Fluid Coming Out When Bleeding?
Generally, when no brake fluid comes out of the bleed port it is due to one of the following reasons: wrong bleeding procedure (operator allows air into the brake system), faulty bleed screw (rusted or with a bad thread), too many air in the brake system, or faulty brake hose.
What is Brake Fluid Made of?
Conventional DOT 3 brake fluids are made almost exclusively of glycol ether whereas newer DOT 4 brake fluids aside from glycol ether also incorporate borate esters to improve dry and wet boiling points. DOT 5.1 brake fluids are essentially made of poly glycol ethers and borate esters for that same reason (better dry and wet boiling points) and in general, are fully compatible with DOT 4 fluids. Concerning DOT 5 brake fluids, they are mostly silicone-based fluids with no hygroscopic properties and high dry and wet boiling points. Since they are not glycol-based, DOT 5 brake liquid is not compatible with other types of brake fluids.
How to Remove Brake Line From Caliper Without Losing Fluid?
Arguably one of the most useful tools when working with brakes is the line wrench. To remove the brake line from the caliper without losing fluid, simply slide the open part of the line wrench over the brake line and then slide it onto the hex part of the brake attachment. Then loosen the banjo connector on the brake hose a little. Do not loosen it too much, just enough to have some mobility concerning the caliper and thus avoid brake fluid leaks. Slowly remove the caliper and position it so that you have easy access to the brake line connection. Now you can manipulate the brake hose without losing fluid. When servicing your brakes always remember to replace the copper washer of the brake hose fitting.
Where Does Brake Fluid Leak From?
The most common places to look for brake fluid leaks are the brake master cylinder connections, the brake master cylinder reservoir seals, the front brake calipers, the rear brake calipers/cylinders, and last but not least the brake lines.
Meet the Team!
Our Product Expert
Steve has been maintaining and modifying vehicles for over ten years. He grew up like most of us did: progressing from Hot Wheels & Legos to racing games like Gran Turismo, eventually taking everything apart just to see what made it tick. His career path was pretty clear early on!
Steve is currently a Certified Auto Repair Technician who graduated top of his class; he's rebuilt engines, transmissions, suspension, and everything in between. Steve also runs his own Youtube production covering hot automotive topics called Cars Simplified. He currently terrorizes the streets of New England in an iconic American classic: the Pontiac GTO.
Our Automotive Journalist
Damaso has been in the automotive world since he was 14 years old when his father bought an auto repair shop. Years later, his passion for electronics, computers, and automotive mechanics motivated him to graduate in Mechanical Engineering and venture into the sales of automotive equipment.
For years Damaso worked as a technical advisor assisting car dealerships, tire shops, and even the plants of Toyota and Mitsubishi that operate in his country. He has over 25 years of experience reporting on topics ranging from DIY jobs, technological analysis, automotive news, and more. He is a wealth of information and a valued member of our team.
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