My old 1999 Cordoba 1.9tdi Vario (estate) suffered severe corrosion to the metal parts of the pipes so I had to change them. There is no dedicated drain point so you just have to undo pipes to let the fluid out. If you use a syringe (or some similar device) to suck fluid out of the reservoir there will still be a lot of oil in the pipes and rack itself. There's quite a lot of oil to drain out so you need something like an old 5 litre engine oil tin with the side cut out to catch it in. Then when it stops flowing by gravity if you turn the steering lock to lock (DO NOT RUN THE ENGINE - you'll do the pump no good at all!) The ram in the rack will pump out more for you. When you think you've got as much out as you can connect up the pipe/pipes you slackened (watch out for seals on the unions) and refill the reservoir with new fluid. All this is best done with the front end up on stands - you'll need the front wheels off the ground to wind the steering to and fro anyway - So now you've got everything tightened up and the reservoir refilled so turn the steering lock to lock a few times (ENGINE STILL NOT RUNNING) The ram in the rack will pump fluid round the system and expel air to the reservoir so you will see the level drop. Keep doing this, topping up as necessary, 'till the level doesn't drop any more. Now there should be enough oil throughout the system for you to start the engine (which will drive the pump) without the pump wrecking itself. Still with the front end up in the air (wheels not on the ground) and engine idling, turn the steering gently lock to lock a top up the reservoir as necessary. When all the air (or most of it anyway) has been chased out the level will stop dropping. You will likely find that the level may drop slightly for a few days as the last of the air finds it's way out (then again it may not if there is no trapped air). Don't do this initial bleeding procedure with the wheels on the ground trapped air can introduce shock waves which can do damage to seals etc. (a bit like hydraulic hammer in your house plumbing).
The manufacturers mostly don't specify power steering fluid change intervals but I've found that when you are carrying out repairs on older cars where you have to break into the steering hydraulics the fluid is often pretty foul. My Cordoba was no exception, the fluid looked dark and dirty. I also noticed that the steering definitely felt lighter with the new fluid in. (she had about 100,000 miles on her when I did this) It's logical to me that a change will be beneficial as most steering pumps are vane type so suffer wear to the vanes and seals etc degrade so there is bound to be contamination as it gets older. On my own cars I like to change supposed "for life" fluids, like gearbox oil and power steering fluid, at around 50 to 60 thousand miles (I would align it with the nearest service interval).
Regarding the fluids themselves. Stuff like gearbox oil, power steering fluid and the like are not a regular service item - you're not doing them every year/12,000 miles You may save a few bob buying a generic brand but these fluids are getting very vehicle specific and you use the "wrong stuff" at your peril so I like to buy the actual manufacturer specified item. Often available on line at reasonable prices (but it is unlikely to be "cheap"). Engine oil is perhaps an exception but I would only buy an oil which met the manufacturers recommended specification ie VW 502.00. VW 504.00. VW 505.01. or whatever. Look in your manual it'll tell you. This is even more important than ever with the latest engines and especially the small capacity turboed petrols (like my
Ibiza 1.0 CHZB engine) which really stress their oils.
A final word - which maybe you know already, so apologies if I'm telling you "
how to suck eggs". When maneuvering with large amounts of lock being wound on, for instance parking in tight spaces, DO NOT HOLD THE STEERING HARD AGAINST THE STOP ON FULL LOCK. If you do this the pump will be trying to force the rack against it's stop and you will eventually blow the seals in the rack. If you find yourself hard over on full lock just relieve the pressure on the wheel, let it come back by even as little as a half inch, and the pressure will be off the seals. In fact try, briefly, holding the steering hard over on full lock - either way, it doesn't matter - and you will hear the pump working extra hard as the pressure relief valve blows off. If you want to explore generic fluids there are a number of websites where you can put you reg no in and see what they recommend - Opie oils is a good one for choice and all the majors like Castrol etc do it too. A good slightly cheaper brand is Comma but the list is almost endless - another reason why I like the manufacturers recommended product (but not at dealer prices)
I hope you find some of this useful - I'm afraid I'm a bit of a "haver" so sorry for the length of the post. If you've never done the sort of things I'm talking about above I'd make sure you have a knowledgeable friend to
help you the first time. A leak makes an awful mess and, of course, can wreck the whole power steering system if a lot of oil escapes or you don't properly bleed it and so run the pump dry. Of course it's all gone electric now but I liked the hydraulic system on my Cordoba better. You could feel what was going on under the wheels much better when things got slippy or you maybe went into a corner rather too fast.
PS. Avoiding holding full lock on is also advisable with electric steering. Won't go into it all here. Just let that wheel return a "smidgeon" and take the load off.
