Safeguarding Your Car’s Performance: A Deep Dive intoTransmission Fluid vs. Brake Fluid

Keeping the correct fluids at their appropriate level is a great idea to maintain a vehicle’s performance. Hence, transmission and brake fluids are the two most essential fluids used in a car. People often get confused by considering them the same.

Thus, the topic of transmission fluid vs. brake fluid appears to mind clarifying the distinctions between them. So, what exactly are they? In short, transmission fluid is used in a car’s transmission to lubricate the gears and keep them moving smoothly. Alternatively, brake fluid is used in the car’s brake system.

Both fluids are essential for a vehicle’s overall performance. But they have their uniqueness which makes them different from each other. Therefore, I suggest you read the full blog about the differences between transmission and brake fluids.

Comparison Overview

Both fluids have different purposes and properties. You should pick the correct fluid for each system (braking or transmission) to prevent damage or safety issues.

Here is a brief comparison chart of transmission fluid vs. brake fluid:

AspectTransmission FluidBrake Fluid
PurposeLubricate moving parts inside the transmissionTransmit force from the brake pedal to brake pads/shoes
TypesAutomatic Transmission Fluid (ATF), Manual Transmission Fluid (MTF)DOT 3, DOT 4, DOT 5
CompositionBase oil (mineral or synthetic) and additives (anti-wear agents, friction modifiers, detergents)Base oil (mineral or synthetic) and additives (corrosion inhibitors, anti-wear agents, anti-foaming agents)
Boiling PointAround 400-500°F (depending on the type)DOT 3: 401°F, DOT 4: 446°F, DOT 5: 500°F
CompatibilityCommonly used fluid for car’s transmissionCommonly used fluid for car’s braking system
ImportanceEssential to let the transmission operates smoothly and efficientlyCrucial to ensuring the braking system works effectively and safely

What is Transmission Fluid?

In this part, I will explain transmission fluid’s definition, types, composition, and properties. You will also learn about the function of this fluid in your vehicle in detail.


Transmission fluid is specially formulated oil for vehicle’s transmission system. It can lubricate the moving parts inside your car’s transmission.

According to UTI, this fluid precisely lubricates a manual gearbox’s bearings and metal parts. Ira Toyota also defines it similarly: “…helps make the act of shifting gears less strenuous on your vehicle…”

Transmission fluid keeps the gears cool. Besides, it prevents friction between the gears, which is prone to severe damage over time.

Types of Transmission Fluid

You can find two common types:

  • Automatic transmission fluid (ATF)
  • Manual transmission fluid (MTF)

Composition & Properties of Transmission Fluid

Transmission fluid consists of a base oil like mineral oil or synthetic oil and various additives to improve its performance. These additives can include anti-wear agents, friction modifiers, and detergents.

ATF is designed to work in vehicles with automatic transmissions. It can withstand high temperatures, which automatic transmission generates. Usually, it contains a special additive package to prevent any wear and tear on the internal components.

MTF is used in cars with manual transmissions. It is typically a thinner oil that can flow through the small passages inside a manual transmission. Also, it contains some additives to protect the transmission system from damage.

Castrol, Mobil, Valvoline, etc. popular brands have transmission fluid with around 424-428°F on average. It helps the fluid to withstand high temperatures generated by transmission.

Functions of Transmission Fluid

The transmission fluid uses a series of gears and clutches to transfer power from the engine to the wheels while shifting gears. When the gears move, they create friction and heat. Hence, it can cause damage if you do not lubricate them properly. But if you use transmission fluid, they will remain cool while reducing friction and wear.

What is Brake Fluid?

This part will teach you about brake fluid, its types, composition, properties, and function. Continue reading to identify the differences with transmission fluid.


Brake fluid is a variation of hydraulic fluid. Vehicle owners use it in their vehicle’s braking system.

UTI says, the braking system cannot function if you don’t use brake fluid. You may also need to flush replace brake fluid routinely in modern braking systems after a certain period or levels. (Source)

Types of Brake Fluid

You can find 3 main types of brake fluid:

  • DOT 3
  • DOT 4
  • DOT 5

Please note, DOT refers to the U.S. Department of Transportation.

Composition & Properties of Brake Fluid

Like transmission fluid, brake fluid is also made up of a base oil like mineral or synthetic and additives. This composition can enhance the braking experience of your vehicle. Hence, some common additives are inhibitors, anti-wear, and anti-foaming agents.

DOT 3 brake fluid is a glycol-based item used in most cars. It absorbs water to prevent corrosion and rust inside the brake system. Besides, it has a boiling point of around 401°F. So, you can use it in most cars.

DOT 4 brake fluid is almost like DOT 3. But it has a higher boiling point of around 446°F. You can use this fluid if you own a high-performance or heavy-duty vehicle. It will withstand more generated heat in the braking system.

In terms of DOT 5, it is a silicone-based car fluid. It cannot work with a braking system with glycol-based brake fluids. However, it has a much higher boiling point of around 500°F. That’s why it is ideal for most high-performance and racing vehicles. But you should not use it in regular cars as it works great with specialized applications only.

Functions of Brake Fluid

Pressing the brake pedal applies pressure to the brake fluid. Then, it is transmitted to the brake calipers or wheel cylinders. (Source)

Gradually, this pressure causes the brake pads or shoes to apply pressure to the rotors or drums. And your car stops or slows down.

Maintenance and Fluid Changes

If you change fluid timely and maintain the vehicle well, it will keep the vehicle providing better performance.

Ira Toyota says you should change the transmission fluid every 30,000 to 60,000 miles. But the frequency may get higher if you have a habit of frequently driving in stop-and-go traffic or towing heavy loads.

In general, it’s recommended to change it every 2 years or 24,000 miles. You may need to change the fluid more frequently if you drive more in high temperatures or humid conditions.

Signs that Indicate You Should Change Fluid

You will see signs indicating it’s time to change your transmission or brake fluid.

For transmission fluid, you will experience:

  • Rough or jerky shifting
  • Slipping gears
  • Strange noises coming from the transmission.

For brake fluid, you will experience the following (according to Car Directory):

  • A soft or spongy brake pedal
  • Reduced braking performance
  • A brake warning light on the dashboard

You should follow the instructions from the manufacturer and use the recommended fluid for your car. However, the fluid changing may involve:

  • Draining old fluid
  • Replacing the old fluid with a new one
  • Bleeding the system to remove air bubbles
  • Ensuring leak free system

Can I Use Transmission Fluid for Brake Fluid in My Car?

No, no professionals suggest using transmission fluid as a substitute for brake fluid ever in any car.

You may think that both fluids can lubricate and transmit force. But they have different chemical properties and are formulated for different purposes.

Generally, brake fluid is designed to withstand high temperatures and maintain its properties over time. But transmission fluid mainly keeps the gears cool. Still, if you want to use transmission fluid in the brake system, it can cause severe damage to the system. Also, you may compromise its effectiveness.

Brake fluid can absorb moisture, but transmission fluid cannot do so. So, using transmission fluid will lead to corrosion and rust in the brake lines and other components.

Usually, DOT-rated brake fluids are ideal for a vehicle’s brake system. You may use DOT 3, DOT 4, or DOT 5 fluid accordingly.

Frequently Asked Questions About Transmission Fluid vs. Brake Fluid

Question-1: What happens if I use the wrong fluid in my vehicle?

Answer: Using the wrong fluid in your vehicle can cause severe damage to your vehicle’s transmission or brake system, leading to expensive repairs. I suggest you use what manufacturer recommends for your vehicle.

Question-2: How do I check my transmission fluid?

Answer: To check your transmission fluid, start by locating the dipstick under your vehicle’s hood. Remove the dipstick first. Then, wipe it clean, reinsert it, and then remove it again. The level of fluid should be within the two marks on the dipstick. Also, the color and smell of the fluid can give you an indication of its condition.

Question-3: How do I check my brake fluid?

Answer: To check your brake fluid, locate the brake fluid reservoir under the hood of your vehicle. Hence, the fluid level should be between the minimum and maximum marks on the side of the reservoir. There might be a leakage in the system If the level is low.

Question-4: How often should I change my transmission fluid?

Answer: In general, it’s recommended to have your transmission fluid changed every 30,000 to 60,000 miles.

Question-5: How often should you change the brake fluid?

Answer: You should change the brake fluid every two years or 24,000 miles.

Question-6: How can I tell if my transmission fluid is bad?

Answer: Signs that your transmission fluid may be bad include rough or jerky shifting, slipping gears, or strange noises coming from the transmission.

Question-7: How can I tell if my brake fluid is bad?

Answer: Signs of lousy brake fluid include a soft or spongy brake pedal, reduced braking performance, or a brake warning light on the dashboard.

Final Words

Now, we have concluded the transmission fluid vs. brake fluid conversation. Both fluids enhance the performance and safety of driving a vehicle.

You should use the correct type of fluid recommended by the manufacturer. Also, try to maintain proper fluid levels and change intervals. After all, regular fluid changes and maintenance keep the vehicle running smoothly and reliably.

Still, suppose you have any concerns about fluid levels or performance. Consult a trusted mechanic or check owner’s manual for guidance in this situation.

Thanks for spending your precious time reading this blog.

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