Steering fluid

[zzoldtown]

Hello all, my Leyland Martian steering tank states OM13 mineral oil is to be used but someone prior to my ownership has marked on it that OM33 oil is to be used, now are either of these oil types suitable for use with a more modern power steering pump - namely from a 1993 Cummins C series engine or will the more modern seals in the pump not like it ?

Cheers

[attleej]

We will have to see what more knowledgeable contributors say but I would have thought that ordinary automatic transmission fluid (ATF) would be fine for both.  OM 33 is ordinary hydraulic oil.  So far as the Martian is concerned, I would use ATF.  

What do others think?

 

John

[john1950]

Red ATF Dexron type oil is the oil the Cummins pump was designed to use. It is a very tolerant benign oil, with froth resistant characteristics. 

Edited April 21, 2023 by john1950

[radiomike7]

I would suggest a call to Fuchs or Millers, they are both very helpful. Are you still running the accumulators under the cab or can the Cummins pump cope on its own?

[G8RPI]

I'd be more concerned about the effect ATF could have on the rest system than OM-33 might have on the pump. The pump is probably easier to replace as well.
OM-33 is a straight mineral hydraulic oil ISO-32 viscosity (I use it on my lathe, it's basically the same a as Esso nuto 32 that is specified). I can't see any problem with running the pump on a ISO 32 oil.
ATF is different viscosity depending on type. Dextron III is thicker at 37 and VI is thinner at 29. OM-13 is thicker again at 47 cst.
"Red ATF" is not a specification. If you do want to use ATF it seems Dextron III would be a better choice based on viscosity. Compatiblity with seals etc is another matter.

Robert.

[radiomike7]

1 hour ago, G8RPI said:

I'd be more concerned about the effect ATF could have on the rest system than OM-33 might have on the pump. The pump is probably easier to replace as well.
OM-33 is a straight mineral hydraulic oil ISO-32 viscosity (I use it on my lathe, it's basically the same a as Esso nuto 32 that is specified). I can't see any problem with running the pump on a ISO 32 oil.
ATF is different viscosity depending on type. Dextron III is thicker at 37 and VI is thinner at 29. OM-13 is thicker again at 47 cst.
"Red ATF" is not a specification. If you do want to use ATF it seems Dextron III would be a better choice based on viscosity. Compatiblity with seals etc is another matter.

Robert.

Might that be Dexron?😀

[john1950]

That would be. From experience if Dexron was used in a Hydraulic system it stayed there, if Hydraulic oil was used in a Dexron system to get back to base, it was then drained and flushed. But on some Cat's we used engine oil in everything except Hydraulic brakes.

[G8RPI]

I'd blame autocorrect but it was all me....🙄

[attleej]

Further to my original post and taking into consideration what others have said I would opine as follows:

First of all I have operated a Martian over 1000's of miles.  They are very forgiving in terms of the power steering oil. We put in OM 33 hydraulic oil and OMD75, engine oil without ill effect.  We never had any seals fail on the steering system or indeed elsewhere.  The steering system did not seem sensitive to viscosity of the oils but we did not use OMD 110 or OEP 220!!!.

Dextron II or III is recommended for my Disco 2 but only in order to meet the cold weather requirements of the Active Cornering Enhancement system.  Using anything other than bog standard ATF would, in my opinion, be a waste of money in an antediluvian Leyland Martian.  The correct spec of transmission fluid in an automatic gear-box is important in order to match the friction material and seals.  This is not an issue in an ancient  power steering system.   

Use ordinary ATF and don't lose any sleep!

 

John