Power Steering Drain or Flush: Which One's Right for You?

Stephen Fogel
June 4, 2018

Your car’s power steering system makes it a lot easier for you turn the steering wheel, especially during difficult or low-speed maneuvers, such as parking.

While some newer cars come with electric power steering systems, the vast majority of vehicles on the road today have hydraulic ones. These use power steering fluid, which you’ll occasionally need to top off or change out. 

When you head to the mechanic for car maintenance, you may have to choose between a power steering fluid drain or a flush. Which one is better? And what’s the difference anyway? In general, a drain is all your car will need, which is great since it’s the less expensive option. But there are definitely situations when you’ll want a flush instead. Let’s look at how power steering works, or you can jump ahead to learn more about each service and find out which is best for you.

How hydraulic power steering works 

An engine-driven pump runs the power steering system. The pump contains a cap with a dipstick, and a reservoir for checking and adding fluid as needed. The pump pressurizes and circulates your power steering fluid, which then provides the mechanical assistance to turn the car when you move your steering wheel. 

Under normal conditions, your power steering fluid stays pretty clean. The fluid doesn’t experience the temperature extremes or contamination that your engine oil has to deal with. It can last a long time without any problems.

But that doesn’t mean it’ll last forever. The fluid should be checked regularly, as leaks can develop — do you hear a whining sound when you turn? It’s also possible that your power steering fluid will get contaminated from small bits of rubber, plastic or metal that can accumulate after many miles of operation. 

» LEARN MORE: Get an estimate for replacing your power steering pump 

When to get your power steering fluid serviced

Your best bet is to follow the carmaker’s power steering fluid service recommendation. Check your owner’s manual or service booklet to verify when it should be done. If you don’t find this info in the printed materials, ask your mechanic for guidance.

There are two types of power steering fluid service procedures: draining and flushing. Many auto service shops, both dealers and independents, will recommend a power steering fluid flushing process. But that’s not always your best bet.

Draining your power steering system

To drain the power steering fluid, your mechanic will disconnect the power steering hose that is located at the lowest spot in the car. The old power steering fluid is drained out; then the hose is reconnected, and new fluid is added to the reservoir. As one person starts the vehicle, another pours more fluid into the reservoir to maintain the level as the fluid circulates. Once the level stabilizes, no more fluid is added. Turning the steering wheel back and forth to its extremes several times will bleed any accumulated air out of the system and into the reservoir. Replacing the cap completes the process.

Flushing your power steering system

The power steering flushing process goes a step beyond the draining procedure. The flushing process is often done with a powered flushing machine, which attaches to the power steering fluid reservoir. After the old power steering fluid is forced out, the machine circulates new power steering fluid through the system.  

Get your car diagnosed by a professional

Power steering draining or power steering flushing?

Here are a few guidelines on whether draining your power steering is an adequate way to service it, or if you should have your power steering system flushed:

What does the owner’s manual say? Check your manufacturer’s recommendations on when and how to service your power steering system. If there’s no mention of flushing, it’s usually not necessary, especially if you have followed the recommended service intervals and the fluid looks clear or translucent, and not murky.

Are there any signs of a steering problem? Have you noticed your steering making noise? Does it take more effort to turn the steering wheel than it used to? Does your power steering fluid have debris and particles floating in it, is it foaming, or does it smell burnt?

If you notice any of these symptoms, get your vehicle to a mechanic immediately. Have your power steering problem diagnosed and repaired before it gets any worse. If your fluid is in poor condition and needs replacement, then flushing the system may be the best option in this situation. Ask your mechanic.

Flushing power steering fluid isn’t usually necessary

Less-than-honest auto repair shops have been known to push for unnecessary power steering flushes to make themselves a big profit. They will recommend this procedure as a part of your vehicle service.

But if your carmaker doesn’t recommend it, and you’re not experiencing any power steering problems, you don’t need this procedure. The simpler, less expensive, gravity-driven draining process will remove the majority of your power steering fluid anyway. The main benefit of a flush would be clearing out any contaminants in your fluid. But if the fluid is clean, it doesn’t need flushing.

Stephen Fogel

About the Author

Stephen has been an automotive enthusiast since childhood, owning some of his vehicles for as long as 40 years, and has raced open-wheel formula cars. He follows and writes about the global automotive industry, with an eye on the latest vehicle technologies.

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