[Vwdiesel] Power Steering Fluid

Patrick Dolan pmdolan at sasktel.net
Wed Sep 9 06:12:00 PDT 2009

Just to answer the technical question:

Hydraulic fluids that are going to see high(ish) pressures and small orifices will tear the viscosity modifiers apart in normal oils (such as ATF).  While they might "work" in such a system, they will not stay in grade for the required viscosity index.  Ultra-high performance oils use base stocks with naturally high VI (meaning fully synthetic), and, if required, expensive liquid VI Improver additives.  In the case of VWAG systems requiring Petrosin, there is also a matter of materials soluability where you had better know that the substitute fluid will not disolve the seals and hoses.  Think of the level of incompatibility of brake fluid, and you get the picture.

Glad to hear that some on Audifans have found substitutes, but, for my money, I will gladly blow it (to my aftermarket jobber supplier) for the "right stuff" rather than risk tearing apart expensive and time-consuming hardware to "save" a few bucks.

----- Original Message -----
From: Kneale Brownson <knealeski at sbcglobal.net>
Date: Wednesday, September 9, 2009 6:36 am
Subject: Re: [Vwdiesel] Power Steering Fluid

> The Mobil, Chevron and Shell products I mentioned were found to be 
> relatively similar in performance at the heat ranges specified for 
> the Pentosin hydraulic fluid Audi recommends, and lots of 
> Audifans.com email listers reported successful use.  The only 
> 1980s Audis that used regular ATF were some of the smaller-bodied 
> sedans and coupes that had vacuum-assisted brake systems instead 
> of the hydraulically-boosted brakes.
> --- On Wed, 9/9/09, LBaird119 at aol.com <LBaird119 at aol.com> wrote:
> From: LBaird119 at aol.com <LBaird119 at aol.com>
> Subject: Re: [Vwdiesel] Power Steering Fluid
> To: vwdiesel at vwfans.com
> Date: Wednesday, September 9, 2009, 2:50 AM
>   For some reason I was thinking the A1/A2 PS systems could use 
> ATF like so many cars in the past?  I know the Audi 5k's of the 
> mid 
> 80's would leak all over if anything but the recommended fluid 
> was put into them.  The only substitute I'd heard of prior to this 
> was baby oil.  Smells funny but one shop used it in "dying" 
> systems 
> for people because it was much cheaper and "couldn't hurt!"
>   So the Mobil, Chevron, etc are a substitute for that oil or is 
> that a 
> whole new, proprietary oil they're for?  (it wouldn't surprise me)
>   Then:  How do those compare to the oil my '96 Passat calls for?
> Why can't they just use hydrualic oil or universal tractor fluid 
> or 
> something!  :-P
>      Loren
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