Power Steering Fluid Maintenance

An easy way to maintain your power steering fluid

Pint-for-pint, the one or two quarts of power steering fluid required by your passenger car are probably some of the least appreciated fluids under the hood. Considering what it does, and how much a motorist depends on it, we're talking about the lifeblood of your steering system. Yet keeping it clean and doing its job doesn't require all that much effort.

The function of this fluid is basic: transmitting hydraulic pressure to make steering easy-but achieving a seamless system operation over a wide variety of conditions is not. The fluid must perform consistently in any situation, from sub-zero to triple-digit temperatures, and both ambient and under-hood temperatures. It also must function when the engine is at idle or full-throttle, and under high pressure, all the while providing adequate lubrication to pump and control valve assemblies, maintaining integrity of rubber components in the system, and promoting noise-free system operation. And your fluid has to do all of these things over an extensive period of time!

Transfer Tool

Of course, these demands take their toll on the fluid and break it down, which can lead to inconsistent performance and expensive component failure. Although vehicle manufacturers haven't generally specified in the past when to actually change the fluid, some are doing this now, or they have designed a fluid that they feel will last "the life of the vehicle." Of course, your opinion on a vehicle's lifespan may differ from that of the manufacturer. That said, we'll share a couple of relatively simple and mess-free methods for maintaining the fluid for a much longer period.

If your vehicle's manufacturer recommends a fluid change interval, definitely follow that. Do-it-yourselfers will need to consult a service manual for the procedure on their particular vehicle. If there is no recommended change interval, however, here's a good rule of thumb to follow: Change it as often as you would your engine coolant. Power steering fluid of the "long-life" variety should be changed every five years or 100,000 miles. For conventional fluid, the interval is every three years or 50,000 miles. Most likely, the fluid will appear normal at this point-either amber (on most vehicles) or pink/red in color. This is good, as no serious problems are indicated.

Filler Cap

As with other vehicle fluids, changing before visible deterioration occurs is ideal. The fluid should be checked at every routine service interval, but if at any time before the interval recommended here, it appears significantly darker than new fluid, it should be changed at that time. Use the following easy procedure for evacuation and filling.

Simply withdraw only the fluid that's readily accessible in its small reservoir, and replace that portion with fresh fluid. You'll be doing this several times over a week or so until the fluid color looks normal. To use this technique, you first have to acquire the proper tool. It's sold as a "fluid removal/transfer tool" or battery filler, and resembles a turkey baster (but that's made of different materials, so don't use one of those from your kitchen). You'll also need to purchase the proper type and amount of fluid as indicated in your manual. Older vehicles use automatic transmission fluid, but later-model vehicles use some form of mineral-based fluid with a "universal" type fluid sufficing as a replacement. Other vehicles, such as Honda and Mercedes-Benz, require a very specific type of fluid.

Next, locate the reservoir and remove the filler cap/dipstick. Withdraw what fluid you can with your newfound "fluid removal tool," being careful not to slop, spritz, or squirt the fluid carelessly on the engine. If you do, immediately and thoroughly clean the spill up with a shop towel. Dispose of the used fluid responsibly, as you would do with used motor oil. Now, fill the reservoir up to the recommended mark on the dipstick ("cold" or "hot") and then start the engine. Cycle the steering from left to right a couple of times, and do a final check and correction of the level.

Final Check

If the fluid is only somewhat darker than new-but not dark brown-you can perform this procedure on consecutive weekends (or a little more often, if you can't stand the suspense!) until you get the desired "good as new" fluid appearance. If the fluid is dark brown or black that indicates a serious system contamination (likely due to breakdown of internal rubber parts or hoses) and more extensive repairs are called for. In this case, solvent flushing is not recommended, as it won't stop the internal breakdown described, and will likely make it worse.

Just as with fluid maintenance for your cooling system and transmission, it's not necessary to change all of the power steering system's fluid to keep it in good condition—as long as it's being done before visible deterioration occurs.


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