Most of us are pretty conscientious about both checking fluid levels and doing regular maintenance by changing them, including transmission, transfer case, front and rear ends, lubing the U-joints and steering components, and under the hood: engine oil, brake fluid, coolant, and checking power-steering fluid levels.
But let's stop right here at the last one, powersteering fluid. The drill is to unscrew the cap off the pump or reservoir and take a look at the fluid level as marked on the attached dipstick. Yep, right where it's supposed to be; and why wouldn't it be? Unless you have a leak, which would be pretty obvious, there is nowhere for the fluid to go. The steering system doesn't burn the fluid, nor does it evaporate. In fact it could be a sealed system, and in practicality it really is.
But think back-when was the last time you changed the fluid? Never! Most likely, that's the answer you will come up with. Generally, you won't even see a mention in an owner's manual about changing power-steering fluid, or if there is one, it will be, like, at 50,000 to 60,000 miles. In reality, miles aren't the important factor here. Pump operation time and heat are the deciding factors, especially on a vehicle used off the highway.
Most roads are laid out in straight lines. When you're driving down them, very little turning takes place, which means very little fluid is being moved, and for the most part the power-steering pump is just idling along doing no work. But let's hit the trail: now we're constantly turning the wheel, making that power-steering pump earn its keep. Not only that, but it has to work a lot harder on the trail than it ever did on the highway. Not only does it have to overcome trail obstacles, it has to fight against a much wider tire footprint and a tire that is driving instead of just being pushed along.
Pressures can reach well over 1,000 psi and fluid temperatures in excess of 300 degrees F. Petroleumbased lubricants don't like temperatures much over 250 degrees. When the power-steering fluid breaks down, metal-to-metal contact takes place with resulting wear. Now we have small pieces of metal circulating within the system working as cutting tools, causing even more wear.
Solutions: Number one is to make it a habit of once a year changing out the fluid. Kind of a pain, I know. What I do is stick a siphon hose into the reservoir and drain it out. I guess you could use Mom's turkey baster, but it might not make her too happy. Then refill the reservoir, run the engine, and turn the wheels left to right to circulate the fluid, bring it back up to temperature, and then siphon it out again and refill. The hotter the fluid, the better, as this helps assure that any crud is being carried in suspension.
Number two is to use a quality power-steering fluid. Sure, you can use ATF, and maybe it will work just fine. But ATF has friction modifiers specifically designed to work with the clutch packs and bands that automatic transmissions use. Use the right stuff! Consider a synthetic power-steering fluid as it withstands higher temperatures so much better and lubricates better in cold weather (as I write this, the temperature here in Montana is -17 degrees F).
Number three is to get serious about installing a power-steering cooler. It's not that hard to cut into a return line (yes, I said "return line," not the pressure side line) and extend the line over to a small oil cooler.
One year at Moab on the Hell's Revenge trail, I damaged my power-steering cooler and had to bypass it. While sitting on the front of my Jeep, watching others tackle an obstacle, I happened out of curiosity to put my hand on my steering box-and very quickly removed it. Pouring some water over it made little dancing balls. Yep, it sure was hot.
Here is a little test you can do to check the condition of the fluid. Keep in mind that it may not be entirely accurate. I call it the "paper blotter test." Grab a common household white paper towel and place a drop of power-steering fluid on it. The fluid should disperse and be red or light brown. If it's dark and does not spread out, it's oxidized and it's definitely time for replacement.
Change the fluid once a year, add a power-steering cooler, inspect the lines on a regular basis and you should have trouble-free operation for lots of years.