PS Fluid vs. ATF

[Falcon_LS]

More and more manufacturers are coming up with their own power steering fluid, whilst others continue to recommend ATF for use in their power steering systems.

I'm just wondering - in what way does the chemistry of PSF defer from ATF? Thank you.

 

[c3po]

I am thinking that both ATF and Powersteering Fluid are Hydraulic Fluid.

 

[Falcon_LS]

No question about that. But I'm curious as to why they are labelled differently. Does PSF have a different additive package of some sort?

 

[Kestas]

I'm led to believe that ps fluid is just like transmission fluid, but without the additives that ATF has.

This is especially important for older vehicles that specified ATF such as Dexron II. The ATF we have now - which is supposedly backward compatible - has morphed into something that the original design engineers couldn't foresee when they wrote the specifications, and may be harmful to the older seals and materials.

 

[Falcon_LS]

Interestingly, my SUV specifies Dexron II for PSF but I have been using Motorcraft Mercon V (Dexron III compatible) since it came out. Prior to that, I used Mercon, which was also Dexron III compatible. Dexron II is rather hard to come across.

 

[d00df00d]

As far as I know, PSF is basically ATF without the friction modifiers. I could be wrong, though.

 

[Bulli]

when i put psf the steering was delayed.
when i put in atf it had a better response.

 

[odessit]

Originally Posted By: Bulli
when i put psf the steering was delayed.
when i put in atf it had a better response.

[bad mood]As scientific as it gets...
When posting advices like that, at least provide car info, maybe temp range it was tried at. Oh, almost forgot, this is an Oil forum.... Hmmm We are missing some other info... What could it be...? Maybe PSF/ATF info?[/bad mood]