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fudge1200
Active Member
I know normally you put the same in the power steering as you do the auto box, but as the box is sealed which ATF do I put in.
I also have an S Class the auto box fluid is Red but the PAS fluid is Clear.
I also have an S Class the auto box fluid is Red but the PAS fluid is Clear.
Power Steering, if hydraulic (some of the newer ones are electric) is a hydraulic system, and since ATF will work in ANY hydraulic system, then ATF is what you use.
ATF is, if you like, extra special hydraulic oil, which is why it is much more expensive than hydraulic oil.
A JCB for example, or any other hydraulic equipment, will work perfectly well on ATF, but the difference is price per litre between ATF and hydraulic oil is why hydraulic oil is used in plant. You do not want to be buying 7 x 25 litre drums of ATF to do an oil change on one item of plant.
Since power steering uses so little fluid, who cares about the price premium.
ATF is only red because of the dye. Same as red diesel.
Bottom line.
Use ATF.
Just go to any half decent motor factor such as GSF and ask for a litre bottle of ATF.
If the old fluid was dirty, why not buy and fit a filter at the same time, not an MB expert but it is rare to find the power steering fluid filter anywhere other than in the reservoir on top of the pump.
HTH etc
ATF is, if you like, extra special hydraulic oil, which is why it is much more expensive than hydraulic oil.
A JCB for example, or any other hydraulic equipment, will work perfectly well on ATF, but the difference is price per litre between ATF and hydraulic oil is why hydraulic oil is used in plant. You do not want to be buying 7 x 25 litre drums of ATF to do an oil change on one item of plant.
Since power steering uses so little fluid, who cares about the price premium.
ATF is only red because of the dye. Same as red diesel.
Bottom line.
Use ATF.
Just go to any half decent motor factor such as GSF and ask for a litre bottle of ATF.
If the old fluid was dirty, why not buy and fit a filter at the same time, not an MB expert but it is rare to find the power steering fluid filter anywhere other than in the reservoir on top of the pump.
HTH etc
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fudge1200
Active Member
Just been up the Workshop, I have Castol Dexron111, Carlube ATF Q3. Both are Red, I also Bottles of Castrol Hydrolic System Mineral Oil, which is Green, This was used on the XJ40 I had for suspension, could this also be used, I am asking as there are all these products out there, ie what differance is there between Dexron 3 to Dexron 4.
Castrol Hydraulic Mineral Oil is hydraulic oil, not ATF.
use the Dextron or Carlube ATF, NOT the hydraulic oil.
Think of it as "all claret is Bordeaux, but not all Bordeaux is claret"
so "all ATF is hydraulic, but not all hydraulic is ATF"
dexron 2 meets and exceeds all dexron 1 spec, ditto 3 > 2, ditto 4 > 3, same as DOT3 brake and clutch fluid meets or exceeds all DOT2 etc
use the Dextron or Carlube ATF, NOT the hydraulic oil.
Think of it as "all claret is Bordeaux, but not all Bordeaux is claret"
so "all ATF is hydraulic, but not all hydraulic is ATF"
dexron 2 meets and exceeds all dexron 1 spec, ditto 3 > 2, ditto 4 > 3, same as DOT3 brake and clutch fluid meets or exceeds all DOT2 etc
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Number_Cruncher
Active Member
Have a chat with an MB dealer, and find the MB spec for the PAS oil.
Most MBs use different oil in the ATF, PAS, and SLS - you don't just use ATF.
Most MBs use different oil in the ATF, PAS, and SLS - you don't just use ATF.
Number_Cruncher
Active Member
Yes, that's quite true for the older ones. I think you need to go back to at least W123 though - W124s, for example, don't take ATF
Rubbish.
Rubbish because ATF meets or exceeds the spec for MB PAS fluid, part #000 989 88 03, which is just a refined mineral hydraulic oil.
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nick mercedes
MB Enthusiast
Everyone puts ATF in 124s, with no apparant ill effects...
That's because ATF is a subset of hydraulic oil, and PAS fluid is hydraulic oil.
A series 3 ATF or later, eg Dexron III or IV, significantly exceed the spec for "official" MB / Fuchs oil.
Number_Cruncher
Active Member
No they don't!
Many people might do, but not ALL.
And, it's not true to say there are NO apparent ill effects. You don't need to look far to find people with PAS trouble after filling with ATF.
ATF simply isn't the oil specified for these systems.
nick mercedes
MB Enthusiast
Honestly, everyone just uses ATF and no harm is done.
Then the problems weren't caused by the oil.
Correlation != causation.
there is another correlation between opening the system to the (dirty) exterior world, and whatever caused the need to add fluid anyway.
Now, hands up and be honest, how many of you change the PAS filter?
I'll say it again, this is not opinion, it is fact, a modern ATF such as Dexron III or IV meets or exceeds the spec for MB original fluid... ergo IT CANNOT CAUSE ANY BLOODY PROBLEMS.
macabethiel
New Member
I would go to your MB dealer and buy the one for your vehicle using your VRM or Chassis number.
For how often it needs changing its worth the peace of mind a new rack / steering box will cost over £1k so do the right thing and use the MB one you know it makes sense !
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For how often it needs changing its worth the peace of mind a new rack / steering box will cost over £1k so do the right thing and use the MB one you know it makes sense !
.Number_Cruncher
Active Member
You can't say that.
You can suggest it's a possibility, but you can't say it's a certainty.
I certainly do.
Again, that logically does not follow.
As an example, it's quite possible for a modern oil which meets and exceeds older specifications can cause problems when used in older or more basic machinery.
It's a simple point of philosophy - the parts of the PAS system are expensive, and breakdowns are very inconvenient - when a system has an oil specified, to be absolutely sure of compatibility all you do is to follow the spec, rather than making it up as you go along.
