When is it time to change powersteering fluid

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Nov 18, 2020
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Being a wind turbine technician who works a lot with hydraulics i know that normal hydraulic oil is for moving/creating the presure, provide lubrication and provide cooling.
On most installations there is a set interval to change the hydraulic oil because it ages under heat. For example 10 years.

In our (throw away) cars we useally never touch it even though this also sees a lot of heat being in the engine compartment and constantnly being pumped around there is no real standard on replacing it.

On the other hand i think i never heard a case where somebodies pump failed etc... because of old oil. On the other hand useally a system only contains like 1l or less so it doesnt cost much to change it.

Does anyone have any info on this or data on how it was done on older cars where chaning out fluids was still a service thing?

My bmw contains fuchs pentosin chf11s fluid.
 
I also change every 50k, and by change I mean just doing a few drain and fills of the reservoir until the fluid is clean, that is all that is needed.


I don't think the system would have a major failure or anything if you don't change the fluid, but the seals will probably leak and the internals will wear faster.
 
Does anyone have any info on this or data on how it was done on older cars where chaning out fluids was still a service thing?

All I've ever done is use a turkey baster, or something similar, and suck as much out of the reservoir as possible, and replace it once or twice a year. I've found that to be easy, less messy, and it keeps the fluid reasonably clear and fresh.

I generally do it while I'm waiting for the oil to drain when I'm doing an oil change. I just dump the dirty power steering fluid in with the old oil.
 
The first fluid change is probably the most important. 30K is a good number. You can use longer intervals after that.

A flush is required if the steering rack or pump is changed.
 
I'd bet probably 95% of all cars go to their graves with the factory fill of PS fluid. But who knows..... Do the quickie lube places push it as an upsell? I could be way off the mark. There could be some guy out there who pays for a PS flush and fill at every oil change....
Most people ignore PS fluid until their car screams like a banshee while going through a parking lot.
 
I'd bet probably 95% of all cars go to their graves with the factory fill of PS fluid. But who knows..... Do the quickie lube places push it as an upsell? I could be way off the mark. There could be some guy out there who pays for a PS flush and fill at every oil change....
It was a much bigger deal on my E32 which used the steering hydraulic pump and reservoir for the LAD rear suspension. It was my first exposure to CHF oils and I was told "the fluid must always be clean"
 
I've done the factory Honda method before. It's painful to do not because it's hard, but because of all the noise it makes where it seems like it's going to blow up. But it's easy and not all that messy with a little bit of work. I had a shop do it once and it wasn't expensive (less than 10 minutes labor) but I was told they don't really like doing it.

Just remove the fluid return hose and route it to a collection container. Run it and turn the steering wheel lock to lock until it can't do it any more. Then put everything back in place and fill up the fluid slowly. It's not too bad as air is purged rather quickly. I think it might have taken three top offs and it was at the top level. But that noise just doesn't sound right.
 
i'll be honest i do mine every 100k and I'm at 320k on the original pump on my yukon and it's just fine. Used both ps and trans fluid.
 
Many car companies don't list a service replacement interval for power steering so it's certainly done very often (or at all in many cars). Going by the color of the fluid is not very helpful as the replacement fluid goes dark shortly in every car I've replaced ps fluid in. Something along the lines of 10 years or 120K would be reasonable.
 
I used the turkey baster method on my 2011 Kia Soul. Filled it with clean fluid and started the car and turned the wheel lock to lock a few times and repeat. Used about a quart of new fluid and probably got more than half of the old stuff out. The car was at 130k miles and as far as I know it was the original. My 2019 Soul doesn’t have power steering so I won’t have to worry about that anymore.
 
Thanks for all the replies, my car is at 244k miles now/17yrs old and its still the original fluid. My car has active steering which uses zf designed steering rack, its reliable system but if something breaks its expensive.

I saw that one of the lines where the rubber hose is crimped into the metal coupling is almost rusted through, will probably replace that soon. Then i will have to drain it anyway.

I will have to look up how much fluid it uses but i guess its less then a litre.

The chf11s is listed as longlife. What the exact definition is of longlife is still a mystery to us:p but i think 17 years and 244k miles is beyond longlife and probaly pastlife in bmw designers view.
 
Did the turkey baster technique on my SAAB 9-3 @ 92K with CH11 fluid. Steering pump and rack were ok but just preventing any expensive problems.
 
No schedule. I just suck out the reservior with the MityVac then hook it up to the return line and suck till it pulls air. Then fill reservoir and suck it through. Let the reservoir run low so it is easy to put the retuen line back on. Then fill it and Let It Bleed.
 
50k miles for a flush is a good number. Or do like some say and turkey baster it every 5 - 7k mile oil change. Either way will work.
 
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