Does power steering use transmission fluid?

Power steering fluid usage varies by system. In many older vehicles with hydraulic power steering, automatic transmission fluid (ATF) is used as the hydraulic fluid, while some models require a dedicated power steering fluid (PSF). More recently, many cars use electric power steering that relies on no hydraulic fluid at all. So yes, transmission fluid can be used in some systems, but not universally.

Fluid options for hydraulic power steering

The hydraulic power steering systems you’re most likely to encounter fall into two main categories: ATF-based fluids and dedicated PSF. The exact specification depends on the vehicle’s make, model, and year.

• Automatic transmission fluid (ATF) as the hydraulic fluid in many hydraulic power steering systems.


• Dedicated power steering fluid (PSF) specified by the manufacturer, which is not ATF and may have distinct additives and viscosity.


• In some older or non-standard setups, other hydraulic oils might be used, but these are less common and should follow the manufacturer’s guidance.

In practice, the fluid choice is determined by the vehicle manufacturer and model year; using the wrong fluid can cause seal damage, leaks, or poor steering performance.

Identifying your system and maintenance tips

If you're unsure whether your car uses ATF or a dedicated PSF for the hydraulic system, these indicators and steps can help clarify.

• Check the power steering fluid reservoir cap and labeling. A cap labeled “Power Steering Fluid” usually indicates PSF; a cap or documentation noting “ATF” or a Dexron/Mercon specification points to ATF being used.


• Consult the vehicle’s owner’s manual or official service data for the exact fluid specification.


• Be aware that newer vehicles with electric power steering (EPAS) may not have a hydraulic fluid reservoir at all.


• When in doubt, consult a dealership or qualified mechanic before replacing or mixing fluids.

Incorrect fluid use can compromise steering feel and reliability. If your car has EPAS, it will usually require no hydraulic fluid and may be diagnosed differently from traditional hydraulic systems.

Maintenance and compatibility tips

Never mix fluids. If you discover fluids have been mixed, flush the system according to the service manual and refill with the correct type. Use the exact specification and viscosity recommended by the manufacturer, and replace the fluid at intervals specified in the manual or by a technician. If your system has a leak or mechanical wear, address the issue promptly rather than simply topping off with a different fluid.

Summary

Power steering fluid usage is not universal. Many older hydraulic power steering systems use ATF or a dedicated PSF, while electric power steering systems do not use hydraulic fluid. Always verify the exact specification in your owner's manual or with your dealer, and never mix different fluids. The right fluid choice preserves seals, pump life, and steering performance.

Can power steering affect transmission?

Yes, pouring the wrong fluid can affect a transmission, especially if power steering fluid is accidentally put into the transmission's reservoir. This is because power steering fluid is not designed to provide the necessary lubrication or friction for the clutch packs in an automatic transmission, leading to slipping, rough shifting, and potentially severe internal damage. Conversely, using transmission fluid in a power steering system can cause damage if the vehicle's power steering system is not compatible with it. 
Consequences of adding power steering fluid to a transmission

• Damage to components: Power steering fluid can degrade seals and clutches, leading to premature wear and potential failure of the transmission's internal components. 
• Shifting problems: The incorrect fluid can cause erratic shifting, harsh shifts, or the transmission's inability to engage gears properly. 
• Overheating: The wrong fluid can lead to overheating of the transmission, a sign of internal damage. 

How to address the issue

1. Do not drive the vehicle: If you've put the wrong fluid in, avoid driving the car to prevent further damage. 
2. Drain and flush the system: Immediately drain all the fluid from the transmission and perform a thorough flush to remove any remaining contaminants. 
3. Refill with the correct fluid: Refill the transmission with the manufacturer-specified automatic transmission fluid (ATF). 
4. Monitor for issues: After refilling, pay close attention to the transmission's performance. Watch for symptoms like slipping, rough shifts, or noises. 
5. Seek professional help: If the symptoms persist, have a professional mechanic inspect the transmission to ensure there is no internal damage. 

This video explains how power steering and transmission fluids are different: 58sJoshua BertschyYouTube · Jan 2, 2018

How to tell if it's power steering fluid or transmission fluid?

They are interchangeable. The only difference between power steering fluid and transmission fluid is that the detergents in transmission fluid are absent in power steering fluid.

Is transmission fluid used for power steering?

It depends on the vehicle; while some older vehicles can use automatic transmission fluid (ATF) for power steering, many newer cars require specific power steering fluid to avoid damage. You should always check your owner's manual to determine the correct fluid for your specific make and model, as ATF contains different additives than power steering fluid that can harm modern systems.
 
When transmission fluid can be used

• Older vehicles: Cars from the 1970s and earlier often use ATF for power steering because their systems are less sophisticated and were designed to handle it. 
• Some specific makes: Certain models, like some older Fords and GM vehicles, were designed to use ATF for both systems. 
• As a temporary top-off: In an emergency, you could use ATF as a temporary top-off, but it's not recommended for long-term use. 

Why it's not recommended for most modern vehicles

• Different additives: ATF is formulated with friction modifiers and detergents for the clutches in a transmission, which can damage the seals in a modern power steering system.
• Specialized requirements: Modern cars have more delicate and specialized components in their power steering systems that require a specific fluid engineered for those parts.
• Harmful to seals: Using the wrong fluid can cause seals to deteriorate and lead to system failure. 

What to do instead

• Check your owner's manual: The safest and most accurate way to know what fluid to use is to consult your vehicle's owner's manual. 
• Use the recommended fluid: If your manual specifies a dedicated power steering fluid, use that. It may be a synthetic or specialized fluid depending on your vehicle. 
• Use ATF only if specified: Only use ATF in your power steering system if your owner's manual explicitly states it is acceptable. 

What fluid is used for power steering?

Power steering systems can use different types of fluids, including automatic transmission fluid (ATF), synthetic power steering fluid, or mineral-based power steering fluid. The correct fluid is determined by the vehicle's manufacturer, so it's crucial to check your owner's manual or the reservoir cap to confirm the right type for your specific car to prevent damage to the steering system.
 
Types of power steering fluids

• Automatic Transmission Fluid (ATF): Many vehicles, particularly domestic ones made before the year 2000, use ATF in their power steering systems. 
• Synthetic Power Steering Fluid: Newer vehicles often require a specific synthetic fluid, engineered to provide superior performance and longevity. 
• Mineral-Based Power Steering Fluid: Some systems use a conventional, non-synthetic fluid. 

How to find the correct fluid

• Check the owner's manual: This is the most reliable source for the correct fluid specification.
• Look at the reservoir cap: The required fluid type is often printed directly on the power steering fluid reservoir cap.
• Consult a professional: If you cannot find the information, an auto parts store or a mechanic can help you identify the correct fluid. 

Important: Using the wrong type of fluid can damage steering system components like the pump and seals, or cause reduced steering performance, so it is critical to use the fluid specified by the manufacturer.