Generic Power Steering Fluid??

[Dr. T]

Last week while driving through upstate NY in subzero conditions, I was exiting the highway to get gas and as I applied the brakes while turning, a huge moan came from the power steering pump and continued as I came to a stop.

Clearly I needed to add more Pentosin that I did not stock in my trunk. Since it was almost midnight, everyone except Walmart was closed. Online search shows that they stock a “Pentosin substitute” made by Prestone called “Prestone Power Steering Fluid for European Vehicles” show here:

http://prestone.com/products?detail=AS268Y

I purchased a bottle of Generic Power Steering Fluid at the Mobil station, poured some in and made my way to the Walmart for the Prestone stuff which required 2 bottles to bring up to level.....at least it was green.

Was it OK to use Generic Power Steering Fluid? Any possible damage caused with short term use?
Anybody use the Prestone stuff? Should I immediately drain and refill with Pentosin?

[CaifanSC]

Dag, that really sux Dr. T! No experience using fluids other than the recommended Pentosin, but from what I recall reading, the issue with using fluids other than what is recommended is wearing on the pump due to the different properties. Since you were not completely empty and only topped off, perhaps any risk is reduced. I, however, would do a flush and refill with fresh fluid just to be on the safe side.

[Dr. T]

Yeah, I knew not to use ATF, but had no other choice at the time. Hope it survived the 30mi. highway trip to Walmart. From what I could tell, the generic power steering fluid is way thicker than Pentosin and would create cold temp issues (wear). Hopefully, it got subsequently watered down... There really should be a low Pentosin warning light!

[Sniff38]

Now that you have your car home, my recommendation would be to flush the system entirely and put one type of fluid in there. But you first have to ask yourself what caused the fluid level to get so low and address that issue. The E31 hydraulic system is rather complex with plenty of places to leak.

The E31 calls for either CHF 11S (fully synthetic) or CHF 7.1 (mineral based) fluid depending on the year/model. I've read many posts that caution against mixing these types of fluid. Your system needs one or the other, but should not be operated with both. So unless you can confirm exactly what's in your system, I'd recommend a complete flush for peace of mind and to reduce any risk of possible damage. What that damage would be I'm not exactly sure, but there's bound to be someone with more knowledge than me who can chime in.

Sean

[Dr. T]

Ever since I can remember, there has been a slow drop in the Pentosin level during the winter. I believe that the hydraulic system depressurizes while sitting in extreme cold and this causes the stuff to squeeze/weep out of any weak spots in the system eg. hose connections. Never did figure out exactly where it’s coming from...maybe should on my springtime agenda!

I never mixed CHF 7.1 and 11s. Just said that the Prestone stuff says it’s a substitute for either. Mine calls for 11s, but since 7.1 is no longer available for the older 8’s, don’t see why they couldn’t use 11s instead. I call bs on that one.

However, I agree that the system needs flushing with new fluid ASAP......

[JDP530]

Ever since I can remember, there has been a slow drop in the Pentosin level during the winter. I believe that the hydraulic system depressurizes while sitting in extreme cold and this causes the stuff to squeeze/weep out of any weak spots in the system eg. hose connections. Never did figure out exactly where it’s coming from...maybe should on my springtime agenda!

I never mixed CHF 7.1 and 11s. Just said that the Prestone stuff says it’s a substitute for either. Mine calls for 11s, but since 7.1 is no longer available for the older 8’s, don’t see why they couldn’t use 11s instead. I call bs on that one.

However, I agree that the system needs flushing with new fluid ASAP......

I have not come across a DIY on flushing the power steering system in case anyone has it bookmarked. Thanks,

[Dr. T]

Not sure there is one... all I’ve done in the past is turkey baster to the main reservoir (after reimoving the filter) and then drain out the rest from small circular filter housing located at the front of the engine oil pan area. Replace both filters and install new fluid.

[JDP530]

Not sure there is one... all I’ve done in the past is turkey baster to the main reservoir (after reimoving the filter) and then drain out the rest from small circular filter housing located at the front of the engine oil pan area. Replace both filters and install new fluid.

Thank, T! I was planning to suction out fluid from reservoir and replace filter but I did not realize that was another filter where more fluid could be drained.

[Sniff38]

I drained my power steering system at the pump. There is a small aluminum drain plug that takes a hex bit. If you drain it here you don't have to use the turkey baster method as this will drain the reservoir as well. I have an ASC+T car so I also drained it at the brass bowl at the front of the engine below the drive belts. I believe this is the lowest point in the system. There is also a metal filter in that brass bowl that can be cleaned and reused.

If you decide to use the pump drain plug be sure to have some hi-temp thread sealer handy. I did not at first and it took me three times to finally get a good seal.

[Sniff38]

I never mixed CHF 7.1 and 11s. Just said that the Prestone stuff says it’s a substitute for either. Mine calls for 11s, but since 7.1 is no longer available for the older 8’s, don’t see why they couldn’t use 11s instead..

All is not lost for those of us with the older E31s as FEBI does still make a CHF 7.1 equivalent. It's called "M6162" and is available at AutohauzAZ and ECS Tuning. It's the green mineral based oil that was originally used in the early E31's.

The point I wanted to make with my earlier comments is the importance of not mixing synthetic and mineral based oils as that doesn't play nicely with our hydraulic system. If you have a car that calls for 7.1, all my research indicates it's OK to change to CHF 11S as long as you flush the entire system of the old stuff. And getting a complete flush is more involved than many think.

Just curious, was the Prestone you bought at WalMart synthetic or mineral based? I don't see how it could be a substitute for both as those fluids are quite different.

Sean

[Dr. T]

I wonder if it’s the same group of people who fictionally say you can’t mix conv. motor oil with synthetic....

Preston’s bottle says it’s synthetic.


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[shogun]

It is mentioned on the Pentosin cans not to mix Pentosin CHF 7.1 and 11S.
On the other hand my wrenching buddy is mixing it since about 10 years and no problem. But officially it should not be mixed.
There is substitute stuff for Pentosin for 7.1 and also 11S from Febi Bilstein, I use that too, even cheaper than Pentosin.

[cartoonz]

Mixing isn't recommended.
However, if you flush out all the mineral based CHF 7.1, you can replace it with CHF 11s - but you need to flush it really well
...and the drain plug IS the way to go.

[shogun]

Someone in Germany contacted in 2011 Pentosin and this is the reply not to mix 7.1 and 11S. 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.

Good day mister xxxxxxx,

Thank you for your inquiry. Both hydraulic oils CHF 7.1 and CHF 11 S mentioned by you must not be mixed, as incompatibilities of components in mixing can occur, which in the worst case can lead to failure of the hydraulic system. This applies to refills, as for fills. We hope to have helped you with this and remain, Best regards, German Pentosin-Werke GmbH.

[bdiefAZ]

I agree, if you want to freshen the fluid, the drain plug is the simplest and most effective way to drain.

What do you guys use when the drain plug leaks. One of the cars in AZ has a leaky plug in the pump.

[Sniff38]

I agree, if you want to freshen the fluid, the drain plug is the simplest and most effective way to drain.

What do you guys use when the drain plug leaks. One of the cars in AZ has a leaky plug in the pump.

I used Permatex #14 (80631) thread sealer on my drain plug. I actually called Permatex technical support and explained what I needed. This was their recommendation.

If you've never drained fluid from the pump before, make sure you have a broad catch pan handy. That stuff comes out pretty fast and will look like a horse pissing on a flat rock.

Sean