Power Steering Issue 1987 Porsche 928 S4 on delivery

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15 Dec 2014 09:47 #17811 by PorscheBob
Got delivery of my car and the carrier had damaged it. A boot covering a line or possible the one on the driver's side of the steering rack was shredded, it is leaking power steering fluid, there are scuffs and paint chips where there were none in the photos taken the day the car was loaded, driver's side seat was wracked and stuck (they apparently didn't realize the car had power seats and 'adjusted' it by pulling up on a drive cable) and then there is the 13 unexplained miles that somehow got put on the car between the time it was loaded and the time it arrived at my house. I was obligated to go with the carrier choice made by the seller but this is disturbing to say the least. Nothing to do but never allow myself to get put into that situation again and deal with the issue as it exists. But, since I now have to deal with a claim...

I got the seat fixed over the weekend by a mechanic who makes house calls so that I can at least get into and drive the car. Now the problem is I have to drive the car to get damage estimates for my claim. I need to replace the leaking PS fluid to the proper level and I've been told it won't hurt to drive the car a couple miles if I bring the level to the middle of the indicator lines on the reservoir cap with Dextron 3 automatic transmission fluid. Which is fine except that the fluid that is in there now is golden in color and Dextron 3 ATF is, of course, red. I'm no mechanic but I know it is NOT a smart move to be mixing different type fluids inside a closed hydraulic system. Just wondering if one of you who are fairly well versed in the subject would have an educated guess as to what gold color viscous hydraulic type fluid might have been used in a Porsche 1987 928 S4 power steering system instead of the Porsche recommended Dextron ATF 3. Also feel free to weigh in if a) you think this fluid might have been aggravating the problem and b) if you believe driving the car once the fluid has been added would cause damage to the rack or hydraulic system. I am also assuming after adding fluid I can leave the lid off the reservoir and turn the steering lock to lock to remove air then add additional fluid if necessary and replace the cap? Thanks.

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12 Jan 2015 00:59 #17921 by Rich928
The Porsche 928 uses Dexron type ATF in both the automatic transmisison and power steering pump. There are different generations Dexron, II, III and IV are common (II and may be obsolete by now), as well as many companies market Dexron/Mercon that meets both standards.

The new Dexron V probably is not suitable for our Porsche 928s.

Rich
Membership Chairman
Charter Member
1993 928 GTS Cover Girl
1987 928 S4
1979 928 5-speed rescue
1979 928 5-liter track beast

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12 Jan 2015 20:35 #17927 by LummoxPG
I know that ATF is a hotly debated issue with 928 owners and the automotive world in general...but here's what I know from people who know more than me. Dexron 1 is a lubricant... derived from whale oil. And ever since the whale oil trade was outlawed the industry has been trying to replicate it...and so far...the original whale oil is still the best. Dexron 2 was the first the mineral oil alternative they came up to replace Dexron, and Dexron 3, which Porsche recommended for my 88 S4, is superior to the now unavailable Dexron 2. Dexron 4 is superior in its ability to lubricate over Dexron 3, and the latest incarnation is Dexron 5 which is a synthetic based lubricant which is even closer to the original whale oil based Dexron 1 in it's ability to lubricate and protect moving parts. That said...in 1988 Porsche recommended 10w30 engine oil for the 928 but have since recommended 0w40 as it has become available...so it stands to reason that as newer and superior ATF's are produced that they would work better in your tranny, and

1988 Porsche 928 S4/SE
1993 BMW 535 i
2001 Mercedes CLK 320

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12 Jan 2015 20:42 #17928 by LummoxPG
oops cut myself short there...and I can attest to much smoother gear changes in my S4 since I replaced the Dexron 3 with synthetic ATF by Mobil. I imagine that Porsche will someday, if they haven't already, recommend Dexron 5 for our transmissions. In fact if I knew where to get a sperm whale I'd be squeezing its juice into my car right now...jus sayin. On a further note when faced with a stubborn nut or bolt I've used ATF as a lubricant to great effect...

1988 Porsche 928 S4/SE
1993 BMW 535 i
2001 Mercedes CLK 320

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20 Jan 2015 22:32 #17942 by wallyp
GM has killed all licenses for Dexron III, and no longer monitors, tests, or controls any Dexron III. You are totally dependent upon the manufacturers and their marketing weasels to maintain the quality and specs - you can no longer get "approved" Dexron III.

This is an excerpt from a GM tech paper:
"...All licenses for DEXRON-III expired at the end of 2006 and will not be renewed. Fluids sold in the market after that date bearing claims such as "suitable for use in DEXRON-III applications" or similar wording should be avoided, because 'DEXRON-III' fluids are no longer checked and policed by GM and therefore may not be the originally tested and approved formulation."

There was/is no Dexron IV or Dexron V.

The current spec is Dexron VI. It is much more tightly controlled by GM, to the point that GM flatly says that any fluid meeting their spec and approved as Dexron VI is good. Several folks have changed their transmissions to Dexron VI with good results.

Now - just a tiny little problem. GM doesn't recommend Dexron VI for anything other than transmissions. Their engineers privately say that it should work fine - but they have not, and will not, test every power steering system in use to ensure that. So, we can use uncontrolled, unapproved fluid sold as Dexron III, which might or might not meet the original specs, or we can use a better transmission fluid (Dexron VI) that might or might not be great power steering fluid. It might be germane that newer Nissan and Infiniti vehicles (and perhaps others) do approve Dexron VI for power steering systems.

Wally Plumley
928 Specialists
www.928gt.com

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