On Dec 4, 2013, at 8:27 PM, thewestyman <zolo@FOXINTERNET.NET> wrote:

There was Power steering fluid filled into the reservoir of the power steering system, and the guy only found out later that it was supposed to be ATF.  
What to do?
Zoltan

Besides price, the main differences are these: Tranny fluid is a highly stable hydraulic oil with a heavy detergent additive, while power steering fluid is manufactured with a friction modifier, and no detergent additive. Both oils will do the job, but in the high pressure/high heat environment of the PS pump and servo, PS fluid will begin to break down sooner than the ATF. Additionally, because of the detergent package in the ATF, particulates and contaminants are held in suspension, while PS fluid will allow these to settle out and likely accumulate where you probably wouldn't want them to. 

It's okay if you keep the PS fluid in the system, but I would certainly not leave it in for too long, my reasoning being that if VW designed the system to use ATF, there was probably a good reason to do so, including the possibility that the operating loads of the Vanagon system exceed the lifetime design limits of PS fluid. 

If/when you flush your system, take the time to replace the PS filter - your seals will thank you!

bob