Hope this might help me and others:
I have just been scanning HJ's excellent advice on buying and selling cars and noticed, in the checking out a car section, that he says PAS fluid should be changed every 2 or 3 years.
I have never heard this said before, or noticed it as part of any servicing recommendations in a manual.
Does anyone else (dis)agree, or care to tell me why it needs a regular change?
I'm confident HJ's comment is well founded, it's just that I don't understand.
Ta
Andy
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The fluid is hydroscopic and obsorbs water. Due to the expansion/ contraction of the oil it is vented to free air thus the source of humid air. Always a good maintenance point to change this oil every 3 years.
Regards
Peter
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Sounds like my cars are (i)9 months and (ii)3 years overdue for a change. I'll add it to the list next time they're in the garage.
Yet another omission from the manufacturer's schedules or can I not read?
Thanks!
Andy
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I've never seen any schedules written down for when to change the PAS fluid. I don't know anyone that has ever changed it either - apart from if the system springs a leak and it needs fixing that is. All the manual states for all the Vauxhall's I've ever owned is to top up as and when necessary.
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I'm guessing my fluid is original after nearly 14 years - the HT leads were and they were knackered. So far it's still fine. The steering is much heavier than modern cars though, but still far lighter than anything without PAS, which is good.
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I wonder, has anyone experienced a problem as a result of not changing PAS fluid? Pump corrosion perhaps?
Thanks
Andy
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I agree with the comment that most maintenace schedules do not detail the Steering oil but the clarity of the oil is a good indication and this oil not only powers the system but lubricates it as well so for a fivers well worth changing it. Regards Peter
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The power steering fluid was changed in my Triumph 2500 five years ago so it must be terribly overdue! On the other hand, I didn't change it from when I bought the car in 1975 until I overhauled the steering rack in 1998 at 207,000 miles -- and I have had no problems with it at all.
On my other car, a 1992 BMW, the power steering fluid is also the self-levelling suspension fluid and I doubt if that has been changed in its 120,000 miles. Again, no problems.
Why not just follow the vehicle maintenance schedule?
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If the fluid remains perfectly transparent then fine if you can not be bothered or do not have a conductance meter. If you do then you can test the fluid for changes against new fliud and decide for your self. My Golf is very stable but the Volvo seems to age and appreciate a fluid change at about 3 years and I have taken Volvos over 250,000 miles. Regards Peter
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I think there may be some confusion here with brake fluid. Brake fluid is vegetable oil/alcohol based and *is* hygroscopic.
PAS systems typically use a Dexron-type automatic transmission fluid (ATF). This is an SAE30 mineral oil with various friction modifiers, anti-foaming agents etc. - this is *not* hygroscopic and does not normally need to be changed. It will degrade through shear of high-temp oxidation; not normally encountered in a PS system. Main reason to change it is because it gradually becomes contaminated with small particles of debris from the system internals. Some cars, such as MB's, have a replaceable filter element to help keep the fluid clean.
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A friend of mine was a Chassis Engineer and worked on PAS systems (he's now an Engineering Manager). I asked him sometime ago if he'd recommend whether I should change the PAS fluid (Dexron II ATF) in my Rover (then 4 yrs old with 100k). He said no need to - only time to put new fluid in is if you've cooked the steering or drained it for some other reason (eg a repair).
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We have just passed the tenth anniversary of this thread. Do our expert regulars have any fresh info to add on this topic?
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