Power steering fluid is a hydraulic fluid that is crucial for the proper functioning of a vehicle’s power steering system. It helps transfer power from the steering wheel to the steering gear, enabling effortless steering control. Like most automotive fluids, power steering fluid deteriorates over time. But does it really expire and go out of date? Let’s take a closer look.
What is power steering fluid?
Power steering fluid is a specially formulated hydraulic fluid that is designed for use in a vehicle’s hydraulic power steering system. It has the following key functions:
- Transfers power from the steering wheel to the steering gear
- Lubricates components in the power steering system
- Prevents corrosion in the power steering system
- Seals and cushions valves and pistons
- Transmits hydraulic pressure
- Removes heat from the power steering system
The fluid contains lubricating oils and additives that give it a high viscosity index to perform well across a wide temperature range. It helps dampen noise and vibrations and has anti-wear, anti-foam, and anti-corrosion properties. Power steering fluid is different from types of fluid used in other vehicle systems like brake fluid, transmission fluid or motor oil.
Does power steering fluid expire?
Strictly speaking, power steering fluid does not really have an expiration date. Automakers typically do not specify expiry dates for it. However, power steering fluid does deteriorate and degrade over time and use.
Some of the ways power steering fluid breaks down over time:
- Oxidation – Exposure to air causes the fluid to oxidize. This reduces lubricity and forms deposits and sludge.
- Heat – High temperatures break down the additives and thicken the fluid over time.
- Contamination – Dust, dirt, moisture and leaked fluids contaminate the power steering fluid.
- Shearing – Extreme pressures physically shear molecules, degrading the fluid.
These effects reduce the hydraulic fluid’s lubricity and viscosity. This makes the power steering pump work harder, causing wear and tear. Hardened deposits can also block tiny valves and orifices. All of this ultimately impairs the power steering performance.
So while power steering fluid may not technically ‘expire’, it does deteriorate with use and age. Most manufacturers recommend flushing and replacing it at least once every 30,000 miles or 2 years as part of routine maintenance. This interval may be even shorter for demanding driving conditions. Replacing old fluid restores optimal power steering performance.
Signs your power steering fluid needs changing
Here are some signs that your power steering fluid has degraded and needs to be replaced:
- Whining noise from the pump – Contaminants in old fluid can damage the pump causing it to whine
- Difficult steering – Thickened, degraded fluid makes the system work harder to steer
- Leaking fluid – Seals and hoses can leak as contaminated fluid damages the seals
- Lack of power assist – Sludge from degraded fluid blocks the system
- Low fluid – Leaks or burning fluid due to pump damage
- Smelly fluid – Fluid has oxidized and needs changing
Catching deteriorated power steering fluid in time and replacing it can minimize wear and tear on the power steering components. It restores smooth power assist for steering ease.
How long does power steering fluid last?
There is no exact expiry limit for power steering fluid. The expected lifespan depends on several factors:
- Vehicle make and model – Some power steering systems are designed for longer intervals between fluid changes than others.
- Driving conditions – Stop-go driving in cities causes more shear and wear than highway cruising. Hot climates also cause faster thermal deterioration.
- Mileage – Power steering components simply wear out from use over time and mileage. Higher mileages demand more frequent fluid changes.
- Fluid quality – Higher quality fluids using more stable base oils and additives last longer.
- Maintenance – Well maintained systems with clean fluid reservoirs and less sludge last longer between fluid changes.
On average, most vehicle manufacturers recommend flushing and replacing power steering fluid at 30,000 miles or 2 years. Some may advise shorter 15,000-mile intervals for heavy duty use. Regular fluid changes are essential, regardless of mileage intervals.
Can old power steering fluid damage the power steering system?
Yes, degraded and contaminated power steering fluid can definitely damage the power steering system. Some of the potential damages include:
- Pump wear – Sludge and varnish cause the pump to work harder leading to wear
- Rack and pinion wear – Loss of lubricity wears out internal sliding surfaces
- Corrosion – Acidity from oxidized fluid corrodes metal components
- Valve sticking – Contaminants block precision valves and orifices
- Seal leaks – Hardened, cracked fluid deteriorates seals causing leaks
- Noise – Lack of lubrication causes whines and groans, especially on startup
Even small amounts of sludge or moisture compromise power steering operation. Catching deterioration early and changing fluid prevents significant wear and expensive repairs down the road.
Does the color of power steering fluid matter?
Yes, the color of power steering fluid offers clues about its condition:
- Clear and amber – This is fresh fluid and should be topped up as needed
- Cloudy brown – Indicates some oxidation and contamination
- Black – Severely oxidized and burnt fluid that needs immediate changing
Power steering fluid is designed to be light amber in color when new. As it ages, the fluid tends to darken towards brown, then eventually black as it oxidizes and thickens. Cloudiness or dark black color indicate depleted additives and varnish deposits.
It’s not advisable to just keep topping up discolored fluid without draining old fluid from the system. This builds up contaminants gradually damaging the power steering components. A full flush and fluid replacement restores the correct amber hue for optimal lubrication.
How to check power steering fluid level
Regularly checking the power steering fluid level and condition is simple:
- Ensure the engine is cold before checking fluid levels. Heat expands the fluid providing false readings.
- Locate the power steering reservoir under the hood. It is typically marked with power steering fluid cap.
- Wipe any dirt from the reservoir. Remove the cap and check the fluid level.
- The fluid level should be between the MIN and MAX marks on the reservoir when cold.
- Inspect the fluid condition and color. Clear amber fluid is ideal.
- Top up with manufacturer approved fluid if required. Don’t overfill.
- Replace lid and check for any leaks from the reservoir.
Checking fluid levels as part of your regular under-hood checks goes a long way in early detection of any potential power steering fluid issues.
How to flush and replace power steering fluid
Flushing out old contaminated fluid and replacing it should be done every 30,000 miles or 2 years. Here are the steps for a DIY fluid flush:
- Ensure vehicle is level and engine is cool before starting.
- Locate power steering reservoir cap and access port underneath the reservoir.
- Place drain pan under the access port to collect old fluid.
- Twist open the access port and allow fluid to drain completely.
- Inspect drained fluid for color and contaminants as an indicator of component wear.
- Obtain manufacturer approved replacement fluid based on vehicle model.
- Refill the reservoir with new fluid and reinstall the access port.
- Start engine and allow to idle. Turn wheels full left and right to bleed air out.
- Recheck fluid levels and top up if required. Replace cap.
- Drive vehicle and recheck for leaks, noise or steering issues.
Flushing the system regularly with new fluid maintains smooth power steering performance for the long run.
Can you mix different types of power steering fluid?
It’s not advisable to mix different types or brands of power steering fluid:
- Mixing DOT 3 and DOT 4 brake fluids deteriorates the performance and properties of the higher DOT 4 grade over time.
- Likewise, mixing synthetic and non-synthetic power steering fluids reduces the benefits of full synthetic fluid.
- Mixing fluids with different additive packages can form deposits over time.
- Topping up with non-approved fluids may void warranty in case of damages.
Stick to the vehicle manufacturer’s recommended fluid grade and specification for the power steering system. Never top up or mix different fluid types or brands to avoid compatibility issues. Flushing the system completely with the correct new fluid type is ideal.
Best power steering fluid brand
Some of the top power steering fluid brands include:
| Brand | Known for |
| Mobil 1 | Synthetic formula resists breakdown |
| Castrol | Premium conventional and synthetic formulas |
| Prestone | Trusted name for a variety of automotive fluids |
| Pentosin | OEM manufacturer approved formulas |
| Lucas Oil | Range of heavy duty and stop leak additive options |
| Royal Purple | High performance synthetic formulas |
Always check for manufacturer approval before using a particular brand. The vehicle owner’s manual will recommend the right specifications and grade of fluid for that model.
Conclusion
While power steering fluid doesn’t really have a set expiry date, it does deteriorate with age and use. Contaminants cause it to thicken and degrade, damaging power steering components. Signs like difficulty steering, whining and leaks indicate the need for replacement. Flushing the system and refilling with new fluid every 30,000 miles or 2 years helps maximize power steering system life. Choosing the right fluid grade and brand based on manufacturer specs also prevents issues. With proper care and maintenance, your power steering fluid can work optimally for long without any expiration issues.
