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Power Steering Fluid Filtering

new 8./11/03

From: Mike Durko 

I couldn't agree more. In a past life I went to training by Avis (the car rental folks) to own an oil change franchise. They were emphatic that if a car had more than 30,000 miles and the trans fluid had never been changed, DON'T Touch it. The varnish is what's holding it together. Some years later I owned a 1990 Souper Coupe and had it into a Furd dealer in Barrington, IL for an oil change. The service writer insisted I also change the transmission fluid. The car had about 57,000 miles and I declined. The service Manager then convinced me it was the right thing to do. At 59,980 miles the car was back at the dealership with a toasted tranny. 4th gear no longer existed. Fortunately, my 60,000 mile ESP still had 20 miles on it and I was back on the road for the $25 deductible.

My question is, does the same logic hold for the power steering fluid change ?


From: Ron Porter

No, it does NOT hold true for PS systems, especially the Gen 3 rare-and-costly-replacement ZF rack. Flush the PS fluid on a regular basis.

I have heard about this "don't change the tranny fluid" old-wives-tale for years, and it is the dumbest damn tranny myth I believe I've ever heard!!

If anyone believes that varnish and deposits will keep a tranny running forever, I have a bridge to sell you.....as well as stock in a penny-stock company that CAN'T MISS!! 

You are just buying time......the tranny is gonna go eventually. Even if it has been 60-80-100K since the fluid was changed, I would do it anyway. The belief that not changing it will keep the tranny running is false economy....if that's the case, it WILL die.....and it will die at a time that is the most inconvenient for you.

Besides, this is a SHO ATX tranny.........it is a maintenance replacement part just like brake pads, mufflers, or tie rod ends.

The Avis folks were just covering their asses......and it had nothing to do with what was the best for the customer.

Ron Porter 

From: Bill Hayward 

With heavy particulate loading suspended in dirty fluids, abrasion & fluid flow reduction from sludge / varnish restricting orifices & filters occurs - taking its toll on mechanical components. In a neglected fluid system, I would still change the fluid but would look at a much earlier filter & fluid changeout interval.

There is no filtration in the PS system to trap fine or large micron particles. As the fluid particulate increases, so does the wear. As Ron said, flush the PS on a regular basis.

A refinery client of mine had slide valve failures in a catalyst system with micron particles above 2 (40+ is the smallest a human eye can detect) & the system was very sensitive to dirt loading in PPM counts. Fortunately, automotive systems are designed with a higher tolerance but the key is to keep the system clean & running within designed operating limits.

Bill H.

You can easily put in a Magnifine filter for the PS system. Cost less than $20.00. www.bulkparts.com has them. Be sure to get the 1/2" size.

FWIW once the fluid is changed, if you refill with a synthetic ATX fluid it will stay clean for years. If the present fluid is very dirty it may take a few flushes to get clean. I drained my reservoir and refilled with cheap ATX fluid until it stayed clean (on my '93). This took about 6 or 7 drain/refill cycles. Then flush with the good stuff.

Paul Nimz
'97 TR

I agree Paul. My '93 has one of the dirtiest PS systems that I've seen - even after several fluid changes...then half-way gave up figuring the cost of fluid would exceed the price of a new rack when the fluid became dirty quickly - should have doubled the change-outs...heheh. From the looks of the fluid turning gray, it almost seems that the rubber hoses may be partly responsible?

FWIW, Paul has done a lot of research in coming up with a compatible PS filter for the Gen III.

Bill H.

Gray is from the aluminum particles in the system.

Glen Murdock
Port Lavaca, TX
97 PG 102k

That makes perfectly good sense...thanks Glen!
My system is rejuvenating itself... :)

Bill H.

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