jimbo3

Well, after being assured by a self-proclaimed "expert", I changed out my original Dextron PS fluid with Pentosin CHS 7.1 as it needed topping off and the proper Dextron III D isn't readily available. After sucking virtually all the Dextron out of the reservoir, I filled with the CHS 7.1, but have NOT since run the engine.

Now I find out that the spec calls for CHS 11S and that CHS 7.1 may not be compatible. Is this correct and, if so, what do I now do so as to not cause any damage? I'm about to schedule an annual visit to the local indie shop- should I simply suck out as much as I can of the 7.1 and refill with 11S and drive the 8 miles to the shop and have them thoroughly bleed?

Geez, I can't believe I did this....

Garth S

Read through this link .... they take the position of compatibility between the fluids, for the only difference is synthetic vs. mineral base.
I faced this recently, and could not get Pentosin CHS 11S locally: rather than use the mineral based Febi/Bilstein 7.1S, I used Febi/Bilstein S 6161. The latter is a full synthetic claimed to be the exact equal of the 11S.

Anyway, I would not lose any sleep over having poured the 7.1 into the reservoir: if the 11S ( or S 6161) is available, whip out the turkey baster again and suck the reservoir dry. Fill with the juice of choice, jack the front wheels off the ground, start the engine and cycle the steering side to side a couple of times to fully cycle and mix the fluids.
Drain the reservoir and repeat the cycle twice more: go for a drive, and perhaps drain and refill the reservoir twice more .... you are doing progressive dilutions of the old ATF, and 5 such cycles should do it .... and use up the liter of synthetic, leaving >99+% syn. in the system.

BTW, if you started this episode due to the reservoir being low .... check out the boots on the steering rack: if the missing ATF resides there, well .... BTDT

jimbo3

Thanks, Garth. The cold sweats have subsided. Blaufernugen even goes so far as to cross-reference the same Porsche part number for both the 7.1 and the 11S. Still, I'm wondering if the Dextron IIID is mineral or synthetic based and whether or not it is totally compatible with the 7.1.

Before starting this project, the dipstick had been about half way up the lower section (halfway between the end of the dipstick and the first notch), but I don't really know where it was reading when I purchased the car 2 years ago, so I have no reference as to how much was actually lost.

Since I already planned to take the car in for routine service, I'll just have the mechanic crack open a fitting, bleed out all of the old and replace with 11S. I already suspected that I have a leak in the rack after having seen some old oily looking dirt around the lower front suspension , so changing out the fluid will be required anyway if that's the case. It wasn't leaking 2,000 miles ago, so I'll keep my fingers crossed.

JasonAndreas

When in doubt always ask the manufacturer and in this case they warn, "Pentosin CHF 7.1 is due to the additive employed not miscible with modern high performance hydraulic fluids like Pentosin CHF 11S !! If fluid change has to happen please refer to previously used original fluid, otherwise damages may occur." The other thing to check is your VIN to see what fluid you were originally filled up with? Although I guess 7.1 is also not compatible with ATF?

Porsche is no longer using CHF 11S and is instead filling with CHF 202. For future reference the porsche part number is #000-043-206-56.

Robin 993DX

Jason, when did Porsche started to use CHF202?

As a side note, about over 5 years ago when I replaced my steering rack (leaking), I just used regular ATF DexIII fluids to fill up the reservoir. 50k miles no issues.

JasonAndreas

I don't have any documentation with a date on it so I have no idea when they started using CHF 202, sorry.

ATF fluid was the original fill and is not supposed to be a problem except for in the 993TT.

jimbo3

My larger immediate problem is if the 7.1 is compatible with the Dextron. They are both mineral based, so there might be a fighting chance that they are. I've contacted Pentosin seeking their advice and will post it. Since I'm having routine maintenence shortly, I can have the mechanic thoughly drain, flush and fill with 11S. Just don't want to do any damage between now and then.

jimbo3

OK, I've heard from Pentosin regarding the (lack) of compatibility between Dextron III and CHS 7.1. Their English answer was simply to remove the 7.1 and flush & fill with 11S. I was able to decipher some of the German from a tech's email in the thread and it said that Dextron III was not compatible with CHS 7.1 and also refered to the Porsche TSB about the 11S.

The good news was that O'Reilly's Auto Parts (where I advised to purchase the 7.1) has the 11S and volunteered to swap out the remaining 7.1 at no charge. At least I don't have the priviledge of paying for the fluid twice!

Will follow Garth's advice about repeating the drain and fill a few times with the 11S to cycle most of the old Dextron (and 7.1) out of the system. I had planned to do this anyway, so no real harm done.

dcdude

Hmmm...so the Lucas PS "stop leak" fluid is no good? I assume it's mineral based. I bought some based on a lister's recommendation, but I have yet to pour it in....

jimbo3

If you're contemplating a "stop leak", maybe you already have nothing to lose??

pcar964

Is there any potential damage to the PS pump with the stop leak stuff? Or is the only potential damage here to the rack, in which case a leaky rack is already bad so no big deal ?

JasonAndreas

Could you PM the german response to me and I will have someone here translate it to english.

jimbo3

Thanks, Jason. I received your translation.

For anyone interested, a technician at Pentosin indicated that CHS 7.1 is a zinc-based lubricant which may have compatibility problems with Dextron III and the two should not be mixed. CHS 11S can be mixed with Dextron III.

My note- This is only as it applies to the power steering system.

-Jim

Slow Guy

I went to my local dealer for P 11S almost a year ago, the parts guy showed me the TSB that said Porsche had replaced 11S w/ the 202 for all applications that previously called for 11S. He would not give me a copy of the TSB though.

BMW also uses 11S in many of their applications but believe it or not my local BMW dealer charged me over 50% more for the 11S I bought from them than the 202 I bought from the Porsche dealer (and I DIDN'T get a discount from the Porsche dealer).