Brake Fluid Buying Guide
Now that we’ve reviewed some of the best products out there, it’s time to dive into the weeds on how to find the right fluid for your brake system.
There isn’t one fluid that will be right for everyone, as different cars will require different products. Always check what type your manufacturer calls for. Once you know that, you can hone in on more specific products based on your needs.
Factors To Consider When Choosing A Fluid For Your Brakes
Although fluid for your brakes may seem simple, there are a number of factors you need to keep in mind when choosing a product. Here are some things to keep an eye out for as you search.
DOT Level
DOT (Department of Transportation) levels are an estimate of a fluid’s boiling point. When you brake, a lot of force is transferred through the brake lines, which can cause the temperature to rise. A higher boiling point means the oil won’t be affected by these increases in temperature.
Although you may want to spring for the highest level possible, it’s best to use the DOT level recommended by your car’s manufacturer.
Higher DOT levels will be able to stand up to more extreme temperatures, so they tend to be used for high performance cars. For example, many cars used for racing require premium DOT 4 or 5 brake fluid, while street cars usually only need DOT 3 fluid.
To find out the DOT level required for your car, check the owner’s manual, or speak to your mechanic.
Water Protection
Brake lines can be quite porous, which means that water can get into the fluid. When it rains, water may begin to seep into fluid.
When you brake, the high temperatures can turn this water to steam, which means that the fluid may compress. If you’ve ever noticed that your brake pedal feels soft, with very little resistance, this is likely due to steam in the fluid.
If you live in an area with wet driving conditions, you should pick a brake fluid that has excellent moisture protection. Silicone based products tend to lock out moisture better than oils made with glycol.
Bottle Size
When looking at price for fluid, always check the bottle size. Many producers will try to rope you in with low prices, only to give you a bottle that is half the size of what you’d get from another company.
The standard size is a liter, although many more expensive, high performance fluids will come in smaller bottles.
Oil Base
Not all fluids are made from the same ingredients. Many are synthetic, comprised mostly of silicone, while other are glycol based. Some cars will require a specific type of fluid, so always keep an eye on the ingredient list when choosing a product.
Corrosion Protection
Most fluids will offer some level of corrosion and rust protection. However, some protects do the job better than others, so check the specific ingredients of each fluid if you want a product with extra corrosion protection.
Lifespan
Fluids will vary in terms of lifespan. Many fluids will last around 20,000 miles, but you can find a number of products that will stretch this number even further.
Note that the lifespans provided on the bottle are just estimates. The true lifespan of the product will depend on your car, as well as your driving style. If you use a car for racing, the fluid will wear out much more quickly than it would when used for day to day commuting.
Which Fluid Is Right For Your Brake System?
When choosing a fluid for your brake system, the first thing you should do is check the manufacturer’s recommendation. Most cars have specific requirements, and your brakes may not perform as well if you use the wrong type of fluid.
In general, high performance cars will tend to use DOT 4 fluid, which has a higher boiling point. If you need to brake suddenly, the fluid can handle the high temperatures. By contrast, many street cars only require DOT 3 fluid, as temperatures in the brake lines aren’t as extreme.
If you plan on using your car for racing, you’ll most likely need a premium DOT 4 or 5 fluid. However, not all of these fluids are the same, as their boiling points can vary widely. Make sure you choose a fluid that is rated to perform at the extreme temperatures you’ll get while racing.
Synthetic Or Normal Fluid?
Most synthetic fluids are made out of silicone, whereas normal brake fluids have a glycol base. More manufacturers have moved to using silicone fluid and other synthetics in recent years, although you can still find a number of products made with glycol.
There are advantages to each type. Silicone fluids are almost entirely water resistant, so moisture won’t seep through the porous outer layer of the brake lines. However, they may absorb a bit more air than glycol brake fluids.
It’s important that you don’t mix the two types of fluid, as this could impact performance and make your brake pedal less responsive. If you want to switch to another type, make sure that the lines are fully drained before adding the new fluid.
Which DOT Level Should You Choose?
When choosing a DOT level, you’ll need to consult your owner’s manual. If the manufacturer says that your car needs a DOT 4 fluid, you shouldn’t try to save money by using a DOT 3 fluid instead. You’ll just cause even more issues down the road, and you may get a hefty mechanic’s bill to boot.
Can you use a higher DOT level than what’s specified by your manufacturer? In most cases, yes. If your car requires a DOT 3 brake fluid, you should do just fine using a DOT 4 fluid.
But keep in mind that higher DOT levels tend to come with higher prices. Although you could use a DOT 5 fluid in a car that needs DOT 4, you really have little to gain in terms of performance.
You only need to use a higher DOT level than recommended if you plan on pushing your car to the limits. Otherwise you’re spending more money than needed.
Best Fluids By Category
There’s no one fluid that will be right for every car. Different manufacturers will require a range of fluid types, so it’s difficult to pick one that will work for everyone.
To make things a bit easier, we’ve compiled some of the best brake fluids by category. Keep in mind that even within each category you’ll still find some different types of fluid, so always follow the manufacturer’s or auto repair shop recommendations when choosing a fluid for your brake system.
Best DOT 5 Fluid
DOT 5 fluids are rated to perform at extremely high temperatures, making them suited for sports cars and racing. If you’re looking for the best combination of performance and value in a DOT 5 brake fluid, the Motor Medic M4032/6 is an excellent option.
Made of silicone, the fluid won’t lose its consistency as you brake quickly from high speeds. The formula is also entirely waterproof, so moisture won’t seep into the brake lines and cause steam to form.
Although this fluid is a bit more expensive than other products reviewed here, it’s a good value for its class. It’s cheaper than other high end brands such as Castrol and Motul, with little drop off in performance.
Best DOT 4 Fluid
DOT 4 fluids are designed to hold up to extremely high temperatures, meaning they won’t wear out or boil away when you slam on the brakes. If you need a DOT 4 fluid, ATE TYP 200 is one of your best options.
It has an extremely high boiling point, even compared to other fluids in the same class. It’s used for racing, so will be more than able to handle day to day use.
The fluid also has some of the best moisture protection of any fluid, helping keep water from seeping in through the brake lines.
Most mechanics recommend that you replace your fluid every 2 years. But with the ATE TYP 200 fluid, you can often get three years of use, or 30,000 miles, without a change.
Best DOT 3 Brake Fluid
DOT 3 brake fluids don’t have a boiling point quite as high as DOT 4 products. But for most cars on the street, this won’t be much of an issue. When it comes to DOT 3 brakes, it’s hard to beat the product offered by Prestone.
The Prestone DOT 3 brake fluid has a great boiling point for its class, so you won’t have to worry about excess wear from sudden braking. The moisture protection is also excellent, helping extend the lifespan of the fluid.
The fluid will last you as long as most other fluids in the same price range, and it’s affordable, only costing around $15 for a liter.
Best Racing Quality Fluid
Castrol are known for making fluids that stand out under extreme conditions. If you plan on racing, the Castrol DOT 4 fluid should be at the top of your list.
The Castrol fluid has an extremely high dry boiling point, meaning the fluid can handle even the most sudden stops. It also has a relatively long lifespan, so you’ll be able to slam on the brakes for years without worrying about changing fluid.
The main downside of this fluid is price. Although it gives you some of the best performance for a premium DOT 4 fluid, it may not be worth the investment if you plan on only driving your car on the street.
However, for anyone who plans on racing their car and needs a fluid that can keep up, Castrol is the frontrunner.
Best Value Fluid
A lot of people don’t want to put too much thought into their brake fluid, and simply want the product that will get the job done for the least money. If that’s the case, the MAG 1 is a great option.
This fluid isn’t going to win any awards for performance. But it does work, with a decent dry boiling point and vapor protection. It won’t last quite as long as high-end options, and you shouldn’t put it in a race car with huge brake pads. But if you only use your car for commuting, you should get more than enough performance.
Best Companies
We’ve tried to recommend specific fluids for your car. However, not all fluids will be compatible with every vehicle.
To make your search a bit easier, here are some of the best companies when looking for a brake fluid. Even if the specific fluid we recommend here is not right for your car, you can likely find another product from the same company.
Castrol
One of the industry leaders, Castrol has long produced some of the best automotive lubricants you can buy. The company makes a range of fluids to suit a number of different types of brake systems.
The main downside of Castrol fluids is their price. They tend to be a bit more expensive than other products. But the price is fair for the performance you’ll get. If you plan on racing or have a high powered car, it’s hard to go wrong with Castrol.
Red Line
This is another company with a long history in the industry. Although not quite as high quality as Castrol, Red Line is still a favorite for high performance cars.
It’s a bit expensive, so you may want to choose another company if you’re trying to save money. But if you’re looking for fluid to suit a sports car, you should add Red Line to your list.
Lucas Oil
Like Red Line and Castrol, Lucas Oil is often listed as one of the best producers of automotive lubricants. They also make a range of quality fluids for brakes that are tailored to high end sports cars and race cars.
You’ll have to pay for the brand. But properly functioning brakes are crucial for your safety, so it’s worth investing in a quality fluid.
Motul
The gold standard when it comes to racing, Motul makes high performance fluids that hold up to extreme temperatures. It’s often used by racing teams, as its performance doesn’t drop as temperatures rise.
The downside of Motul fluids is that they’re expensive. Although they’re great for racing, most people aren’t driving Formula-1 cars to work.
Frequently Asked Questions
Can you mix different types of brake fluid?
It depends on the DOT level. In most cases, you’ll have no issues mixing fluid from two different brands if they are both the same DOT level.
However, you should not mix fluids of different levels, especially if your car manufacturer specifies a certain type of brake fluid. For example, don’t add DOT 3 fluid to your car if you already have DOT 4 fluid, as this could impact performance.
How often should you flush your brake system?
It depends on the product you buy, as fluids vary in terms of their lifespan. In general, car mechanics recommend you change brake fluid every 20,000 miles.
How long will it take for a brake fluid flush?
It depends on the type of brakes you have, as well as the type of car. For an experienced mechanic, a brake fluid flush usually only takes a few minutes. If you try to do it yourself without any experience, it may take around an hour.
How does brake fluid work?
Brake fluid is essential for transferring the force when you push down the pedal to the brake rotors. Without fluid, you cannot clamp don’t on your brakes.
As fluid wears over time, water may begin to leak into the brake lines. When there is moisture in fluid, force is not fully transferred to the brake rotors, so you will not be able to stop as suddenly.
How do you know when fluid should be changed?
The fluid is often kept in a clear reservoir, allowing you to check fluid levels by eye. You can also use a number of tests that check for copper in the fluid, which is a sign that it needs to be changed.
Be careful when removing the cap to the brake fluid reservoir, as air can get into the reservoir. This can affect performance and may be dangerous.
If you have an older car, you should also regularly check to make sure that the seal isn’t broken on the reservoir, as this can cause air to leak into the brake fluid.
Do you need a mechanic to change fluid?
No. For most cars, you can handle the change yourself. However, if you have little experience, you may want to have a mechanic do it for you.
How much fluid do you need to add?
It will depend on the vehicle. In many cases, you’ll need around half a liter bottle if the lines are completely dry.
If you are unsure about how to add brake fluid to your car, you can find out more about the process here. If you’re still not comfortable replacing fluid yourself, a mechanic can take care of it quickly.
How much does brake fluid cost?
Although price does vary widely depending on the brand, prices are usually around $10 to $20 for a 1 liter bottle.
Should you top off your fluid if levels are low?
No. If you notice that your brake fluid levels are running low, this could indicate that your brake pads are wearing out. If you continue to replace the fluid anytime it runs low, you’ll just end up using brakes with worn out pads.
Is brake fluid flammable?
Yes, although much less so that gasoline. Brake fluid will catch fire, but it burns fairly slowly. You shouldn’t burn any matches near the bottle, but you also don’t need to worry about it exploding in a ball of flames.
How often should you bleed your brakes?
Bleeding brakes is the process where you release air that has built up in the brake system. It’s an important part of regular maintenance, and can prevent your pedal from getting spongy and unresponsive.
Bleeding brakes is a fairly easy process if you have the right experience. But if you’ve never done it before, brake bleeding can be a bit of a headache. To save yourself the trouble and lower the risk of making the problem worse, you can always have your mechanic handle it for you.
