Can Transmission Fluid Be Used For Power Steering

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As a car owner, you’re likely familiar with transmission fluid. When it comes to your vehicle’s periodic service, you may think can I use transmission fluid for power steering fluid? Because sometimes you may have extra transmission fluids.

There is debate over using transmission fluid for power steering, and these two fluids have different Viscosity Index and Flashpoints. Depending on the vehicle’s transmission system, there are mainly two types of fluids.

In this post, I’ll discuss what transmission fluid is and what power steering fluid is. Can Transmission Fluid Be Used For Power Steering?

Transmission fluid for power steering
Pouring transmission fluid for power steering.

What Is Power Steering Fluid?

The power steering fluid is a fluid used to create a hydraulic connection between the power steering and the front wheels. This fluid transfers the steering wheel power to the front wheel using hydraulic pressure. Power steering fluid change interval every two years or after 50,000 miles.

The power steering system is a metal-on-metal vane design system. In this system, the force given by the driver to the steering wheel is increased by pressure by hydraulic fluid, which is used to turn the front wheel.


What Is Transmission Fluid?

Transmission fluid is a thin hydraulic fluid that helps to transfer power from the engine to the wheels. Transmission fluid is used to cool the vehicle transmission system and hydraulic pressure to internal parts. This fluid ensures that gear transmissions are smoother. Transmission fluid can be made from synthetic or mineral oil. Automatic transmission fluids have many friction additives and metal-on-metal vane design systems.

Here are two types of transmission fluids:

  • Manual transmission fluid (MTF): This type of transmission fluid is used in manual transmission vehicles. The manual transmission system generates lower heat, and this fluid type has a lower viscosity. It is typically brown to amber in color.
  • Automatic transmission fluid (ATF): This fluid is used in automatic transmissions. It has higher levels of detergent and dispersant to help clean the gears and prevent damage, and ATF has a higher viscosity than MTF. This fluid comes in red.

These two fluids are not interchangeable, and they have different viscosity indexes.


Is transmission fluid same as power steering fluid?

Transmission fluid helps move the gears, while power steering fluid helps to keep the steering wheel turning. Many people mistakenly believe transmission and power steering fluids are the same, but they are not.

Transmission and power steering fluids are hydraulic, but the transmission fluid is intended to transfer engine power to the wheel and lubricate the transmission’s gears and bearings, whereas the power steering fluid creates a hydraulic link between the steering wheel and front wheels. Using the wrong fluid type can damage and wear out these systems. 

The main differences between these fluids are viscosity, flash point, detergents, and friction modifiers. Therefore these two fluids are not the same. However, some vehicle manufacturers recommend automatic transmission fluids for power steering. But some vehicle manufacturers recommend using only steering fluids for power steering systems. Therefore first read your car manual. If it mentions you can use automatic transmission fluid for the power steering system, you can use it.


Transmission fluids and power steering fluids technical specification.

We take the same manufacturing transmission and power steering fluids for this technical comparison. You can see that automatic transmission fluids and power steering fluids have a similar range viscosity index, and high viscosity index fluids have less ability to thin as temperature increases.

Product nameProductViscosity
Flash PointSource
Castrol Transmax High MileageATF200356°F(source)
Mobil™ Multi-VehicleAFT193424°F(source)
Valvoline Maxlife Multi-VehicleAFT163396°F(source)
AMSOIL Multi-Vehicle PS197446°F(source)
Castrol Power Steering FluidPS190350°F(source)
Mobil Delvac 1™ 75W-80MTF155453°F(source)
Valvoline Professional MTF177428°F(source)



Can you mix power steering fluid with transmission fluid?

Power steering fluid (PSF) and transmission fluid (TF) are essential to keeping your car in good working condition and reducing premature wear. However, some believe they can mix the two fluids to create a stronger mixture that will improve performance. These two fluids have different additives, detergents, and friction modifiers.

However, this is not always the case – combining the two fluids can damage your car’s steering and transmission systems—especially rubber parts. If you’re considering mixing PSF and TF, consult your car’s owner’s manual first.


What happens if you put transmission fluid in power steering?

If you put transmission fluid in the power steering, it can cause the power steering not to work. Transmission fluid is a type of hydraulic fluid that helps move the car. Putting too much transmission fluid in power steering can stop the wheels’ motion and make it challenging to drive the vehicle.


Is transmission fluid thicker than power steering fluid?

The transmission fluid in a car is thicker than the power steering fluid because it is designed to resist heat and wear. Transmission fluid also contains friction modifiers to help keep the gears moving.



Power steering and transmission fluid are used for different systems in your vehicle, and these two products have different viscosity, additives, and sometimes different base oil. Some automobile manufacturers recommend automatic transmission fluids for power steering systems—for instance, Ford and General motors.

Unless your car manual clearly states that you can use transmission fluid for power steering fluid, you should not use it, which can damage and increase power steering system parts. If you are unsure whether your vehicle can use ATF for power steering, ask your mechanic or vehicle dealer if you have questions about using transmission fluid for power steering.

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