Oil in the power-steering-fluid reservoir: how bad is it?

Dear Car Talk

Dear Car Talk | Nov 01, 2002

Dear Tom and Ray:

I hope you can help a beleaguered father. I need to know how deeply I am mired in you-know-what. I gave my 17-year-old son my old, 1991 Isuzu Trooper when I got a new vehicle. I knew that even though it didn't appear to leak oil, it needed oil every now and then, so I admonished him to check the oil and add some when needed. Last night he was here visiting, and I asked him if he had checked it lately. He said that he couldn't remember. We walked out to the vehicle and lifted up the hood. After checking the dipstick and finding it down a bit, I said, "We should add some oil now." He just stood there looking at me. So I said, "You DO know where to add the oil, don't you?" He promptly took the cap off of the power-steering-fluid reservoir and said, "The last time I added some, it only took a little bit before it started overflowing." Now what? How much trouble am I in? And where can I take it to be fixed without being laughed out of the parking lot? -- Tom

RAY: Well, we have all kinds of good news for you, Tom. Good news No. 1 is that it's only a '91 Isuzu Trooper.

TOM: Good news No. 2 is that it could have been worse. He could have dumped the wrong fluid into the transmission.

RAY: Good news No. 3 is that there wasn't room for him to put much motor oil in there.

TOM: Power-steering fluid is a thinner oil, without many of the additives you find in motor oil. And my guess is that the worst thing that will happen is, eventually, the power-steering pump might get fried. I'd be concerned about the seals in the pump being eaten away by the motor oil.

RAY: The solution is to simply flush out the system. Assuming the pump is not leaking already, just take it to any repair shop and ask a mechanic to drain the power-steering fluid and replace it with new stuff. It can be done manually, or by a machine that sucks out the old stuff and pumps in new stuff.

TOM: And if you're embarrassed, you don't even have to tell the mechanic why you're doing it. Tell him you and your son do it every year as preventive maintenance. And tell him there's no significance whatsoever to the T-shirt you're wearing that says "I'm with Stupid."

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