E36 Bmw what ATF works best in the P/S system?

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So I have a ZF p/s system that takes ATF, I've been flushing it with a baster 10oz a time every 20-50 miles for a while now, I'm on the seventh quart of fresh ATF now. I have used Valv, ST, and Castrol all dexIII/merc universal. I have noticed that all 3 of the brands Ive used are notably different in thickness at room temp when you shake them and make my steering feel differently (heavier or lighter) as I add 1+ quarts of a certain brand to the system. The full system is just shy of 2 qts capacity for reference if the net is right. So far I like the feel of the Castrol which in my shake feel is the middle in thickness with Valv being heaviest and ST being thinnish, 2.5qts if Castrol cycled in now back to back. I am going to fully drain the system and address the OEM hose clamp leaks I have then refill with probably Castrol. I'm wondering what others run in their BMW PS system to get the best effect. The system says Dex3, but 1992 was a long time ago and fluids have changed a lot... what should I run in my P/s for ATF? The internet has tons of conflicting info on the subject and I know there is good feedback to be had here so I was hoping to get a more concrete answer.
 
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I have also emailed ZF to see what fluid they recommend for the system since the spec is long outdated, ill report back with what they say if they respond.
 
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My BMW requires CHF 11S, but if I could use ATF it would be M1 ATF. I use that in both my Toyotas and it holds up well to the heat, staying red and relatively clean looking for quite a while.
 

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The only place I can find it locally is at Fleet Farm for $9 a quart... anywhere you guys have found it cheaper?
 
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It's a p/s system - ANY Dex-III ATF, changed regularly, will work fine and keep the system working great from years to come. High-priced synthetics are a major overkill in this application.
 
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Originally Posted By: KenO
It's a p/s system - ANY Dex-III ATF, changed regularly, will work fine and keep the system working great from years to come. High-priced synthetics are a major overkill in this application.
Until the -20F start up that is when the syn really shines synthetics is never overkill given the small sumps of most p/s systems.
 
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In no way is a synthetic fluid "major overkill" in a power steering system.
Originally Posted By: KenO
It's a p/s system - ANY Dex-III ATF, changed regularly, will work fine and keep the system working great from years to come. High-priced synthetics are a major overkill in this application.
 
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Originally Posted By: kschachn
In no way is a synthetic fluid "major overkill" in a power steering system.
Originally Posted By: KenO
It's a p/s system - ANY Dex-III ATF, changed regularly, will work fine and keep the system working great from years to come. High-priced synthetics are a major overkill in this application.
Originally Posted By: dave123
Originally Posted By: KenO
It's a p/s system - ANY Dex-III ATF, changed regularly, will work fine and keep the system working great from years to come. High-priced synthetics are a major overkill in this application.
Until the -20F start up that is when the syn really shines synthetics is never overkill given the small sumps of most p/s systems.
Fair enough. Difference of opinion I suppose smile
 

lim

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Originally Posted By: Brenden
I have also emailed ZF to see what fluid they recommend for the system since the spec is long outdated, ill report back with what they say if they respond.
Any news from ZF? You will probably find they quote their specification TE-ML 09 which, in April of this year, looked like this! Regards, lim
 
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Having synthetic ATF in a steering system that accepts conventional ATF is not overkill. I have used M1 Dexron III and Valvoline Dexron VI in multiple Toyota cars, and every time I did that, the steering felt lighter. The fluid also stays cleaner over a longer period of time.
 

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Sorry I've been very busy this past week, I did get a response from ZF regarding my question of what fluid to use due to the wide range of universal dex/merc options. From the "service desk" it says... From a ZF perspective Dextron has always been the preferred oil, however due to health and safety reasons the original Dextron was removed. The later / newest levels of Dextron will work and performance should not be effected. BMW also use Pentosin in some of its platforms, this is a mineral based oil and a little more expensive. This can be purchased from BMW stores. The caveat of which is that the complete system has to be flushed several times to purge the old oil from the system. It sounds as though they recommend some/any form of Dex 3+ ATF for the pump to use as a hydraulic fluid, but a clean/fresh fluid to the pump/rack is the most important thing.
 
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