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Virtually all modern vehicles have power steering and the majority are still hydraulic. These systems are reliable and easy to keep that way with a few simple tips.

Basic hydraulic power steering consist of only a few parts. There is a pump which supplies pressure, a steering gear which is powered by the pressure and hoses that connect it all. There is also power steering fluid which is the life-blood of the system. Keeping the fluid fresh can help prevent having to replace the expensive parts.

parts of a basic hydraulic power steering system

Power steering fluid cools, cleans, lubricates, conditions seals and transmits the hydraulic force used to assist steering. With so many requirements it is no wonder there are a number of formulations on the market. Many vehicle manufactures utilize specialized fluid. These fluids are designed to work in specific systems and usually give the best results.

Just a few power steering fluids in common use

There are also a number of system that use automatic transmission fluid for power steering. These systems will normally use the words "Use automatic transmission fluid," Use Dexron" or "Use Mercon" written on the fill cap or in the owner’s manual. Automatic transmission fluid is fine for the systems designed to work with it, but should never be used in a system that calls for power steering fluid.

Dexron and Mercon are types of automatic transmission fluid. Years ago, Dexron was primarily for General Motors and Mercon was intended for Ford. With regard to power steering the names are basically interchangeable today. For instance Dexron will meet Mercon specifications and vice versa. Synthetic automatic transmission fluid will also exceed both specifications.

synthetic automatic transmission fluid works well in Dexron and Mercon designed power steering 

Due to a huge number of factors, no guide can replace individual manufacturers recommendations. The following is a general guide but should be verified for specific applications.  When in doubt, the manufacture specific fluid (*) should be used.

 Make ModelFluid Type 
AcuraAll modelsHonda P/S fluid *
Dodge, ChryslerAfter 1998ATF+4
Dodge, ChryslerBefore 1998P/S fluid
ChryslerCrossfire Chrysler fluid *
Daewoo All models Dexron III 
DodgeSprinter Chrysler P/S fluid *
FordAll modelsMercon
General MotorsAll models P/S fluid
Honda All modelsHonda P/S fluid *
Hyundai Verify models Dexron III 
Jeep2005 up Chrysler P/S fluid *
Jeep 2006 up Commander Chrysler P/S fluid *
JeepAfter 1998ATF + 4 *
Jeep Before 2005 Grand Cherokee P/S fluid 
Jeep Before 1998 all models P/S fluid 
InfinityAll models Dexron III 
Isuzu All models Dexron III 
Kia Verify model Dexron III 
Lexus All models Dexron III
Lincoln, Mercury All models Mercon 
Mazda All models Dexron III 
Mitsubishi Verify model Dexron III or P/S fluid 
NissanBefore 1994 Dexron III 
Nissan1994 upNissan P/S fluid *
SaturnAll models P/S fluid 
ScionAll models Dexron III 
Subaru All models Dexron III 
SuzukiAll models Dexron III
ToyotaAll models Dexron III 

Most power steering problems involve leakage. Over time, seals get hard and debris wears away at the sealing surfaces. Both problems are made far worse by dirty power steering fluid with depleted additives. Replacing power steering fluid is very easy and can prevent a great many problems.

There are only a few cautions to be observed, but they are VERY important. First is to use only the correct fluid. This will normally be listed on the fill cap or in the owners manual.

Second is to be certain to locate the proper fill point. There are several reservoirs under the hood. Mistakes like adding power steering fluid to the brake system can cause immense damage almost immediately. Look for the words Power Steering on the cap.

Lastly, power steering fluid is flammable and under great pressure. I never recommend removing any of the hoses to replace the fluid. Instead a simple partial fluid replacement method is as effective and much safer.

Power steering fluid is flammable, don't take chances

A couple of very simple tools and the proper fluid are all that are needed. Replacing all of the fluid is unnecessary. Simply drawing a measured amount of old fluid from the reservoir and replacing it with fresh fluid works very well.

simple tools needed to replace power steering fluid

With the engine off, remove the power steering cap. Draw out as much fluid as can easily be removed and measure that amount with the cup. Clean the cup and add the same amount of fresh fluid that was removed. Add this amount to the power steering reservoir. 

Bleeding works best with the front wheels raised slighlty off the ground.  Safely block the vehicle in the raised position.  Replace the cap, and without starting the engine and slowly steer from right to left about ten times. This allows the fresh fluid to circulate through the system.  Now start the engine and repeat. Turn off the engine and check the fluid level.

Repeating the above process more than once will remove even more of the old fluid, but a complete replacement is usually unnecessary. A partial replacement every two years will normally keep the additives replenished and keep the fluid fairly clean.

The partial fluid replacement method is easy, inexpensive and can help prevent several power steering problems. The key is not to wait until there is a problem. Early preventative action can save quite a bit.

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