John Berryman wrote:
On Wednesday, February 1, 2006, at 02:38 PM, Donald Snook wrote:

I picked it because that is evidently what Mercedes recommends for a
1990 300SEL.  If I am going to pay the premium price for Mobil 1 ATF or
Amsoil ATF, then I might as well pay the price for the stuff that was
actually designed for the car. It is not as if I am putting in the home
grown parts store brand of power steering fluid.

Is ATF approved for that new-fangled rig? I've drained it and replenished it in many customers cars over the years. I know at one time or another, I looked up that info. I wouldn't think you'd be getting junk from Rusty, furthest thing from my mind. I don't keep PS fluid around, AFIK ATF is good for almost everything.

Mercedes revised the recommendation (236.2) for PS fluid in about 1987/1988 (236.3). They use an oil that's a little less viscous than type A ATF (which is less viscous than Dexron II/III) and that isn't treated with the Lubrisol additives. It is far superior (doesn't stiffen up) to conventional Dexron in very cold weather (although the synthetics that meet the Dexron/Mercon spec seem just fine). The Mercedes fluid is recommended for ALL Mercedes PS systems, but ATF is still permissible for any system that was originally factory filled with ATF (most any car built before 1987). Using ATF in cars up to about 1995 will not cause any major problem, but in cold weather, the steering may be more than a little stiff.

Here's the result of some research on the subject by Dr Eric Chowanietz:

The MB manual transmission oil and PS oil (from memory 262.2 and 262.3 ??)
are basically old-fashioned non-friction modified hydraulic oils - as used
in old auto transmissions and farm machinery ("Type A, Suffix A").  The PS
oil is a very slightly lighter weight than the manual transmission oil.
When you think about it the PS oil has a lot less work to do than the ATF -
it is a much simpler oil.  I'm sure ATF will 'work' perfectly well so long
as you are not in a *very* cold climate where the slightly higher viscosity
of the ATF might pose a problem. Indeed, a modern ATF probably has much
better corrosion-inhibiting properties and lubricates better than these
old-fashioned oils.

MB do not, of course, make their own oils.  The people at the Elf Oil
technical HQ told me that the MB PS oil was supplied by them.  I don't know
if this really is true, but they were able to quote both their own P/N and
the MB P/N right of the top of their heads - which sounded convincing to me.


          Marshall Booth (who doesn't respond to unsigned questions)
      "der Dieseling Doktor" [EMAIL PROTECTED]
'87 300TD 182Kmi, '84 190D 2.2 229Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5 turbo 237kmi

Reply via email to