Is it ok to replace CHF 7.1 with synthetic trans fluid

[genphreak]

Such as synthetic replacements for Dexron II & III?

I know one can change to CHF 11S or whatever. What is the difference- these power steering systems appear to have the same steering box, lines and reservoirs. Perhaps the pumps are different?

How does putting Dexron in a system designed for CHF/Pentosin affect it? I have synthetic Dexron right here... will it blow seals (how could it if its synthetic- surely its very similar to CHF11S)?

[shogun]

I would not do it!!!!

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.
http://www.pentosin.de/shop_produkt.php?c=&pid=668&vid=

[Itsnotme1988]

Isn't Pentosin only for cars with SLS/LAD? The other pumps call for ATF IIRC.

[Morgenster]

I would not do it!!!!

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.
http://www.pentosin.de/shop_produkt.php?c=&pid=668&vid=

I'm still on the fence about this. My mechanic says ATF is no problem for that system and I've been running it for years without issue. What exactly happens when you mix ATF and pentosin 7.1?

[Dave M]

I'm still on the fence about this. My mechanic says ATF is no problem for that system and I've been running it for years without issue. What exactly happens when you mix ATF and pentosin 7.1?

This is good to know and I've often wondered why I spent so much $$ on this dificult to source stuff. Hopefully we gat some sort of consensus.

[Morgenster]

This is good to know and I've often wondered why I spent so much $$ on this dificult to source stuff. Hopefully we gat some sort of consensus.

Well, I'm still on the fence. You never know my power steering could be **** up real fast, but then it'd still be a good question to ask: was it because of the fluid?
ATF is definitely easier to find and every store I go to and ask them to lookup what's supposed to go in there they tell me ATF also.

[shogun]

The question has already been discussed since years on E32 boards. And the decision is:
never replace Pentosin with ATF! Period.

People had damages and people tried to bleed the whole system after the mechnaic or previous onwer put in ATF where Pentosin should be put in.
Leaks occured, small channels blocked then in the system because of abrasive parts and so on.

Just try it, if you want to make your own experience and pay $ for your own experience.
It can be fine for some time/years, but then....
Ask E32 owners which had this problem.

[ryan roopnarine]

i'm pretty sure that bill r, either 3 or 4 years ago, posted an advisory about replacing the atf in non-lad equipped cars with chf 7.1 if the owner was having poor steering performance in really cold climates. i'm pretty sure that this was a bmw document. the document, of course, said that the system must be thoroughlly flushed of the old stuff, though. my car has a cap that says "chf 7.1" but has had atf in it since i bought it. i don't think i've ever seen an e34 with a chf 7.1 cap that actually had chf in it.

[shogun]

Why do you want to risk so many $ in damages. Pentosin you can also buy from VW, MB, maybe cheaper, or you go to RR or Bentley and get your bottle served there on a silver plate :)
http://www.bimmerboard.com/forums/posts/275263/


Some people from the German 7-Forum and also now from the E34 Forum in German had contacted Pentosin. One got the reply by email, the other one talked with a head of a labority there.

To make it short:

1. Where Pentosin CHF 7.1 is mentioned on the sticker of the reservoir, only refil CHF 7.1.

2. A mixing with other hydraulic oils could cause that addititives could separat as a flocculent , which then could block valves etc. The instruction not to mix is mentioned on the cans of the Pentosin 7.1
That is apparently also mentioned in a special internal BMW info for the workshops.

3. CHF 7.1 contains special lubricants/additives, which are required by the older systems on E32 and E34
CHF 11S does not contain these additives in the required volume, it therefore cannot be used as alternative or replacement for 7.1 in case of tpping up and/or replacments of Pentosin 7.1.

4 CHF 7.1 is green; CHF 11 is also green,but the colour is slightly lighter green.

Here a copy of the email received in Germany from Pentosin:

Guten Tag Herr xxxxxxx,

vielen Dank für Ihre Anfrage, beide von Ihnen genannten Hydrauliköle CHF 7.1 und CHF 11 S dürfen nicht vermischt werden, da es zu Unverträglichkeiten von Einsatzkomponenten bei Vermischungen kommen kann, was wiederum im schlimmsten Fall zu Ausfall des Hydrauliksystems führen kann.
Dies gilt für Nachfüllungen, wie für Neufüllungen.

Wir hoffen Ihnen hiermit weitergeholfen zu haben und verbleiben

Mit freundlichen Grüßen
Deutsche Pentosin-Werke GmbH.

[shogun]

And here an old design from IceTea from Netherlands on Readfly how he tried to find out the best way to get all the wrong stuff out his car
http://img337.imageshack.us/img337/7662/selflevelinghydraulicsyki4.jpg

[The Bigfella]

What's this about all the $$$$? Cost me about $20 for a tin. Beats running any sort of risk.

[genphreak]

What's this about all the $$$$? Cost me about $20 for a tin. Beats running any sort of risk.Where i Oz can I get it tho BigFella? BMW, Merc, OMG!

No doubt it needs to be flushed in this car. A tin for $20- whereabouts should I try?

Thanks for the concern everyone, especially Erich- I know the cause/effect paranoia is high on bimmer forums but farout why o why ever use anything other than ATF in such as system... esp when the same model comes with the same stuff and does!

Oh, of course- how silly of me. So you can put in different seals.

I always knew BMW were just playin' with us...

[shogun]

try the others which have the same stuff, maybe you can get it there easier:

Pentosin CHF 11S Synthetic Hydraulic Fluid

Pentosin CHF 11S Synthetic Hydraulic Fluid - Fully synthetic hydraulic fluid for steering and central hydraulic systems. This synthetic fluid is correct for many later models which specify synthetic fluid. Temperature range -40C to +130C. Should not be mixed with ATF fluids or other power steering fluids. ***Note - this is currently sold as part # G00200 by Audi/VW as of 1990, replacing Pentosin CHF7.1 The CHF11S is correct for Audi/VW 1990 and later models, while Audi/VW 1989 and earlier models can use either 7.1 or 11S although 11S is recommended. Audi/VW states that 7.1 and 11S can be mixed if necessary but we suggest draining and flushing the system if you are changing from 7.1 to 11S***

1 liter can. Equivalent to the following: VW/Aud# G002000, BMW# 81.22.9.407.758 and 82.11.1.468.041, Porsche# 000.043.203.33, Rolls-Royce & Bentley# RH5000

15.16

-----------------------------

Pentosin CHF 7.1 Hydraulic Fluid

Pentosin CHF 7.1 Hydraulic Fluid - Special mineral based hydraulic fluid for use in power steering, central hydraulic and suspension level control systems. Should not be mixed with ATF or other fluids. Temperature range -40C to +100C. ***Note - this was sold as part # G00200 by Audi/VW through 1989. As of 1990 Audi/VW is selling Pentosin CHF11S as their part # G002000. 1989 and earlier models can use either although the 11S is recommended. Audi/VW states that 7.1 and 11S can be mixed if necessary but we suggest draining and flushing the system if you are changing from 7.1 to 11S***

liter can. BMW# 81.22.9.407.549, was also *formerly* VW/Audi #G002000

11.30

from:
http://www.germanautoparts.com/chemicals/Steering%20and%20hydraulic%20fluids/Pentosin
---------------------------------------------------------
The biggest difference is the double vane pump instead of a single pump, and of course the seals (maybe).
I have just disassembled a double vane power steering pump and renewed all gaskets and seals. Not that difficult.

[Morgenster]

And here an old design from IceTea from Netherlands on Readfly how he tried to find out the best way to get all the wrong stuff out his car
http://img337.imageshack.us/img337/7662/selflevelinghydraulicsyki4.jpg

Well, I'm getting scared, but the link doesn't work properly, so any other ways to see that method?

[Ross]

The moral of the srory here folks is to repair any leaks so the cost of the fluid is moot once there is no need to continually top it off.
$20 is a bite for a liter of oil but cheap insurance against the cost of overhauling the hydraulic system.

[shogun]

Well, I'm getting scared, but the link doesn't work properly, so any other ways to see that method?

I have it on another server also
http://s71.photobucket.com/albums/i155/shogun_bucket/?action=view&current=BMW750E32HydraulicSystemSchematic.jpg

[ryan roopnarine]

ok, this is getting annoying. if my car had chf 7.1 in it originally, i might feel different. also, i have to agree with ross--if you fix your leaks, the cost is moot. that having been said....


nothing posted here indicates that atf will f' up will mess up a non lad 7.1 system. the pentosin document says theirself that the issue is with putting 7.1 into 11 and vice versa. miscible is a very specific chemistry term. it does not mean that the fluid will destroy anything, it just means that the 11 and 7 will not combine, most likely the 11 will float on top of the 7.1 and appear to look like a different "phase". it is quite telling that pentosin would tell people that it isn't ok to mix the two fluids, but it is ok in a pinch, and that it is ok to do so if you completely flush the system--but that mixing them produces "floucculent". it is hydraulic fluid, it is going to get into everything, but a cursory flush makes it ok? chf stands for central hydraulic fluid, mineral (for 7.1). atf is a hydraulic fluid. pentosin isn't going to be the group to ask for the suitability of mixing the two, zaharand-fabriken (sp?) is, but nobody has bothered to ask them in any of this. i wouldn't ask valvoline if their transmission fluid is suitable first, i'd ask the vehicle manufacturer/transmission manufacturer first. i've had atf in my 7.1 capped vehicle for in excess of 100k miles and the only issue that has resulted is a dead spot on center that has more to do with the age of the vehicle than of the fluid running through the system.

[Ross]

I am cautious from experience. An Audi(that called for 7.1)I once owned had been filled with ATF. Perhaps coincidence but I had to overhaul the pump and the rack. The seals for the pump were made of special material, I noticed that much. I'll let you guys figure out what that cost.
I haven't a clue about the chemistry of these fluids but have a firm grasp of the labor and expense involved to fix an ailing system.

[Morgenster]

ok, this is getting annoying. if my car had chf 7.1 in it originally, i might feel different. also, i have to agree with ross--if you fix your leaks, the cost is moot. that having been said....


nothing posted here indicates that atf will f' up will mess up a non lad 7.1 system. the pentosin document says theirself that the issue is with putting 7.1 into 11 and vice versa. miscible is a very specific chemistry term. it does not mean that the fluid will destroy anything, it just means that the 11 and 7 will not combine, most likely the 11 will float on top of the 7.1 and appear to look like a different "phase". it is quite telling that pentosin would tell people that it isn't ok to mix the two fluids, but it is ok in a pinch, and that it is ok to do so if you completely flush the system--but that mixing them produces "floucculent". it is hydraulic fluid, it is going to get into everything, but a cursory flush makes it ok? chf stands for central hydraulic fluid, mineral (for 7.1). atf is a hydraulic fluid. pentosin isn't going to be the group to ask for the suitability of mixing the two, zaharand-fabriken (sp?) is, but nobody has bothered to ask them in any of this. i wouldn't ask valvoline if their transmission fluid is suitable first, i'd ask the vehicle manufacturer/transmission manufacturer first. i've had atf in my 7.1 capped vehicle for in excess of 100k miles and the only issue that has resulted is a dead spot on center that has more to do with the age of the vehicle than of the fluid running through the system.

I'm going to ask ZF then.

[shogun]

That is not only ZF. ZF just produces the power steering pump and the steering gear.
There is a regulating valve in the engine room, there is a regulating valve at the rear axle, there are 2 shocks, there are 2 "bombs", and if you have a E32 750, there is also the brake booster unit which is also using the same fluid. And there are pipes and hoses connecting the single parts.
Ever checked the price of a regulating valve for LAD? No repair parts available. Ever checked the price of the regulating valve inside the engine room?

The only one which can tell you something for the whole system, is BMW. And for that, have a look into the owners manual.
No need to ask ZF in my opinion.

If you ever have opened a steering gear which is hydraulically supported by this fluid, and see all these tiny little channels etc., (I have done 2 within the last 3 weeks) you would be very relucatant to make any experiment with such a system.
If it fails, it will costs you $$$$

[ryan roopnarine]

i certainly wouldn't tell anyone with lad to experiment. if i didn't, let me make myself clear--all of my posts wrt transmission fluid refer to cars without lad. if your car is sans lad, you should contact zf and ask them about it, it is their box and pump.

[Morgenster]

i certainly wouldn't tell anyone with lad to experiment. if i didn't, let me make myself clear--all of my posts wrt transmission fluid refer to cars without lad. if your car is sans lad, you should contact zf and ask them about it, it is their box and pump.

E-mail is sent. Don't know if they'll reply though.

The website doesn't even mention pentosin. They list a whole variety of ATF manufacturers that are supported. I'm curious to see what the reply would be.
If they tell me to ask BMW that'll be my next step.

@Shogun: I totally agree that compound systems with LAD should be treated with care in this case, but I only have basic power steering and that's it. No leaks BTW.

[ryan roopnarine]

I am cautious from experience. An Audi(that called for 7.1)I once owned had been filled with ATF. Perhaps coincidence but I had to overhaul the pump and the rack. The seals for the pump were made of special material, I noticed that much. I'll let you guys figure out what that cost.
I haven't a clue about the chemistry of these fluids but have a firm grasp of the labor and expense involved to fix an ailing system.


ross, earlier non-lad cars were either equipped with resivoirs that called for either atf or 7.1. i've seen a number of audis with atf in them--when the tank calls for green--and wondered about that. i don't think that the atf in a non-lad car is that big of a deal, seeing as we are considering the matter of an old @ss design recirculating ball box and pump. people with e34s get hydraulic shops to redo their PS lines with generic 3 strand hose all of the time. if the car is non-lad and the weakness isn't with the box or the pump, and generic hose doesn't "flake" off into the system when exposed to 7.1, i don't see where the issue is.

[Ross]

The Audi didn't have self leveling either. Like I said it may have been coincidental.
There must be some difference for BMW to have spent the extra $$ for the initial fill on a zillion cars so not knowing for sure myself I err to the conservative side.
I'm glad the ATF works for you but won't be doing it myself.

[genphreak]

All very interesting contributions. Thanks to everyone for their thoughts on this... Morgenster; it'll be real interesting if you can get a response from the horse's mouth.

[Morgenster]

All very interesting contributions. Thanks to everyone for their thoughts on this... Morgenster; it'll be real interesting if you can get a response from the horse's mouth.

Well this is the official response from the Belgian technical department:

"Dear Mr. Van Rafelghem,



We thank you for your E-mail with the requested complementary information about your BMW.



In order to bring the most appropriate answer to your request about the power steering oil to use, we’ve contacted our Technical Department.



The conclusions of our investigation indicate that the use of ATF oil instead of CHF 7.1 oil is fine, as this oil fulfils all the specifications for the power steering of these models.



Taking into account that CHF 7.1 oil is now less available, many of the garages of our network use ATF oil, which is the power steering oil used in current models of our brand.



We remain at your service for any further information you may want, and wish you lots of driving pleasure in your BMW.



Yours sincerely,





Antoine Langendijk"

edit: I have to add: I specified only power steering. No mention of LAD, so LAD might be different still.

[Morgenster]

Well this seems to have ended the debate:D

[BrianKissel]

Good read, it appears the main isssue between the atf vs 7.1 is that ATF have about double the viscosity.
http://www.candokaraoke.com/tony.html

[Morgenster]

And now the gentle folks from ZF chiming in:

Dear Mr. Van Rafelghem.

Basically I'd recommend to use the oil that is already filled in the steering system. This whould be PENTOSIN CHF 7.1 or nowadays CHF 11S or CHF 202, which all are Cold Climate -Types.

Of course the system would also work with Mineral based oils of ATF - Type.
System should be flushed when changing to this oil - Type.before. Be shure to use ATFs with a DEXRON Approval 2D, 3E,3F,3G.

Hope this will help you.

Mit freundlichen Grüssen / Kind regards
Juergen KNOERLE
Manager CENTRAL LABORATORIES, HQL

ZF Lenksysteme GmbH

[genphreak]

Morgenster, we are in your debt. Excellent work!

I have changed to ATF with great hapiness, however on removing the old oil I emptied the systm and loosened the output pipe at the pump. Running at idle it spat old fluid out until it was running low, whereupon I filled the reservoir with dexron and then tightened the pipe collecting the old oil from the steering gear before shutting down when it went fresh (red). then tightened up the resovoir input and topped up.

Interestingly, the pump had some metal/alloy filings in it, which might be why the steering pump was complaining.... seems MUCH better now though!

Thanks again, btw if anyone wants their steering system to last, make sure you change your fluid- I'd use synthetic ATF for this as you don't want to go changing it too often. However doing it with Dexron a few times seems a good idea (filings are certainly not wanted in there!)

:) Nick