The importance of maintaining the hydraulic brake system of a vehicle cannot be overstated. The hydraulic brake system comprises several components, including the brake fluid, which transfers force and creates pressure to help the brakes function properly. However, brake fluid may need to be replaced occasionally, and car owners may wonder if they can use alternative fluids, such as transmission fluid, as a substitute.
This raises the question: Can hydraulic fluid be mixed with transmission fluid? Transmission fluid is a hydraulic fluid used in automatic transmissions to transfer power from the engine to the transmission. It shares some similarities with brake fluid, such as its function in transferring force, but notable differences exist. For example, transmission fluid has a lower boiling point than brake fluid, which could lead to problems with the brake system.
Despite these differences, some car owners may consider using transmission fluid as a substitute for brake fluid because of its availability or cost-effectiveness. However, this can be a dangerous practice, as it can compromise the vehicle’s and its occupants’ safety.
In our guide, we’ll explore the differences between brake fluid and transmission fluid and the potential consequences of using transmission fluid in a brake system. By the end, you’ll better understand the difference between the two and see what to do if you accidentally mix the two fluids. (Read What Causes A Starter To Burn Out)
What Is Brake System Fluid?
Brake fluid is a type of hydraulic fluid used in vehicles’ brake systems to transfer force from the brake pedal to the brake calipers, causing the brake pads on the rear brakes to clamp onto the rotors and slow down or stop the vehicle. The brake fluid operates under high pressure and high temperatures, so it must have a high boiling point to prevent it from vaporizing and losing its effectiveness.
Brake fluid also must have a low viscosity to ensure it can flow easily through the brake lines and to the calipers. Brake fluid is typically made up of glycol-ether or silicone-based compounds, and it comes in different grades or types, including DOT 3, DOT 4, and DOT 5.1.
Each type has a different boiling point and viscosity, affecting its performance in various weather conditions. Brake fluid is a critical component of the braking system, and it must be adequately maintained to ensure the system functions properly and safely.
If the brake fluid is low, contaminated with alcohol, or has been in the system for too long, it can cause the brake’s rubber seals to fail, resulting in a dangerous situation for the driver and passengers.
What Is Transmission Fluid?
Transmission fluid is a type of hydraulic fluid used as friction modifier in vehicles to lubricate the transmission and transfer power from the engine to the transmission. It withstands the high temperatures and pressures in a transmission system.
Transmission fluid is typically made from a mixture of base oils and additives that provide the properties such as viscosity, oxidation resistance, and frictional characteristics. It is usually red or green and has a distinctive odor. Transmission fluid is circulated through the transmission by a pump and is used to lubricate the moving parts, cool the transmission, and facilitate shifting.
It also helps to transfer power from the engine to the wheels using the transmission. A properly functioning transmission requires the right type and amount of transmission fluids to ensure it operates smoothly and efficiently. Using the wrong transmission fluid or insufficient fluid can cause the transmission to malfunction and potentially cause damage to the vehicle.
Therefore, using the recommended transmission fluid for your vehicle and checking the fluid level regularly is essential. (Read Anti Rattle Where Do The Clips Go On Brake Pads)
Can I Add Transmission Fluid To Brake Fluid?
Your car cannot move without an engine, of course. Also, your power steering enables you to go in the proper direction. But none of that will matter if you can’t stop when you get there. The most crucial safety element in your car is its hydraulic brakes. As you depress the brake pedal, a hydraulic pump pushes brake fluid from the brake fluid reservoir through a network of steel lines and tubes to each of the wheel cylinders and then to the brakes.
The purpose of the brake fluid is to transmit pressure from the pump to the front and rear brakes, which slow and stop your wheels and your car. As a result, the brake fluid needs to be in good shape, clean, and dry. Your brake system will become less efficient if you add anything other than brand-new, non-expired brake fluid to the brake reservoir.
Some drivers incorrectly apply ATF to the brake system in the same way they would the power steering. This must not be done! Your brake system will be destroyed by ATF, which will eat away at the seals in the brake master cylinder and other system parts.
What To Use If You Have No Brake Fluids?
According to many sources, a mixture of soap and water can serve as a brake fluid substitute, while others recommend using alcohol. Brake fluids are Glycol-based hygroscopic fluids, which means it absorbs moisture.
A solution of soap water is the finest solution. This is because of soap’s glycol-based nature and water’s inherent force. Initially, it’s essential to comprehend how the brake fluid in a car functions within the brake system. Only gradually stopping your car safely is the responsibility of the liquid.
When you apply the brakes, the force is used in the master cylinder, which forces the fluid from the master cylinder into the pressure chamber in the brake caliper. Hydraulic pressure from your foot transfers power through pressurized brakes. The brake pads on the brake disk attached to the wheel are pressed against one another as the fluid enters, slowing the car.
While it may seem a good solution for a short time, the first thing to do is head to the auto parts store and get the proper fluid for your brake system. (Learn How To Clean Brake Rotors Without Removing Wheel)
What Will Happen After Adding ATF To My Brake Fluid?
Mixing brake fluid and transmission fluids is not a good idea because they are two different liquids. Combining the two might cause various issues for your car and void its warranty.
Mixing transmission fluid with brake fluid can cause severe problems in your vehicle’s braking system. The main issue is that transmission fluid is not designed to handle the high pressure and temperatures that brake fluid can reach. Brake fluid has a higher boiling point than transmission fluid synthetic oil, which can handle more heat without vaporizing.
When transmission fluid is used in place of brake fluid, it can cause the seals and hoses’ rubber materials in the brake system to deteriorate, leading to leaks and loss of brake pressure. The different chemical compositions of the fluids can also cause corrosion and damage to the components of the brake system, such as the calipers and brake master cylinder itself.
If you happen to put transmission fluid in your brake fluid reservoir accidentally, it’s essential to have the entire system flushed and cleaned as soon as possible. This process involves draining all the contaminated fluid, cleaning the lines and reservoir, and refilling it with fresh brake fluid. It’s crucial to seek professional help from a mechanic or automotive technician to prevent further damage to your braking system.
Here you can see what to do if you find brake fluid mixed with transmission fluid.
- Get a turkey baster, open the brake fluid reservoir, and suck the fluid out.
- Get new brake fluid, jack up your car, and take each wheel off at a time.
- Unscrew the caliper’s bleeder screw.
- Connect a hose to the nipple and place the other end in a glass jar half filled with brake fluid.
- Get a helper to pump the brake pedal until no bubbles show slowly.
- Tighten the nipple and move on to the next wheel.
- You should periodically check your master cylinder during this process to ensure the reservoir does not run out of brake fluid.
- You are replacing the old fluid with new fluid and flushing out your hydraulic brakes.
Other Car Fluids
Here are other fluids used in various parts of your car.
Motor oil/ Engine Oil
Motor oil, also known as engine oil, is a lubricant used in internal combustion engines to reduce friction and wear on metal parts. It is typically made up of base oil and additives that help to enhance its performance. Motor oil serves several functions, including lubrication, cooling, and cleaning.
Lubrication is the primary function of motor oil. It creates a thin film between moving metal parts, reducing friction and wear on the engine. This helps to prolong the life of the engine and improve its performance. Motor oil also helps cool the engine by carrying away combustion-generated heat.
Besides lubrication and cooling, motor oil also has cleaning properties. As it circulates through the engine, it picks up dirt and debris and carries it away, preventing it from building up and causing damage.
Motor oil is available in various types and viscosities, including conventional, synthetic oil, and high-mileage formulas. Using the recommended motor oil for your vehicle is essential to ensure optimal performance and protection. Adding the wrong oil can cause smoke to come from your exhaust. (Read Brake Pad Wear Indicator Inside Or Outside)
Power Steering Fluid
A power steering fluid is a hydraulic fluid used to transfer force within the power steering system of a vehicle. It lubricates and protects the various metal parts of the power steering system and assists in the smooth operation of the steering mechanism.
The fluid is typically made up of synthetic oil and various additives that help to reduce wear on the system’s components and prevent corrosion. Like other hydraulic fluids, the power steering fluid operates at high pressures and temperatures. It also has a lower boiling point than brake fluid, which allows it to function within the power steering system.
The fluid is stored in a reservoir near the power steering pump. Over time, the fluid can become contaminated with moisture and other impurities, leading to damage within the system. As a result, it is essential to periodically flush and replace the power steering fluid to maintain the system’s performance and prevent costly repairs.
ATF (Automatic Transmission Fluid)
Automatic transmission fluid, or ATF, is used in vehicles with automatic transmissions. It is a lubricant and coolant for the transmission and helps transfer power from the engine to the transmission.
ATF is typically red or pink and has a slightly sweet odor. It is specifically formulated to work with the intricate hydraulic system of an automatic transmission, which uses ATF to create hydraulic pressure to shift gears.
It is also used to cool and protect the transmission from wear and tear and prevent corrosion and rust. Most vehicles require periodic ATF changes to maintain proper transmission function and avoid damage.
ATF comes in different grades and types, and it’s essential to use the correct type of ATF for your specific vehicle, as using the wrong type could cause transmission damage or failure.
Engine coolant, or antifreeze, is a liquid mixture of water and chemicals that regulate an engine’s temperature. It typically comprises a base of ethylene or propylene glycol mixed with other chemicals, such as corrosion inhibitors and lubricants.
The primary function of engine coolant is to transfer heat away from the engine and dissipate it through the radiator. It helps to prevent freezing in cold temperatures and boiling over in hot temperatures.
Using engine coolant is crucial to maintaining the health and performance of an engine. Without it, an engine could overheat and cause significant damage. It is vital to ensure that the coolant level is maintained correctly and that the mixture of water and coolant is at the correct ratio for the specific vehicle.
Some vehicles may require a specific type of coolant, such as a particular color or chemical composition, so it is essential to refer to the owner’s manual for guidance. Regular flushing and engine coolant replacement are also recommended to prevent corrosion and the buildup of contaminants.