Whats special about PSF? Or is it ATF?

[ryland]

Is amoil psf just repackaged amsoil atf (the old formulation) or does psf indeed have different additives? Is it ok to use amsoil atf new or old formulation in a car that requires psf?

 

[Gary Allan]

I dunno. I never understood why the market developed dedicated power steering fluid to begin with. ATF had served so many for so long ..but I don't get quite a few evolutions in fluids.

I would think that a power steering fluid would not need to tap dance on the additive end of things to compensate for the transitional mechanisms that are found in the transmissions. There would be no need to assure "velvety smooth shifts" ..or compensate for convert lock up shudder.

I think it's synthetic hydraulic fluid just like any that you may find in a fork lift or tow motor's system.

That said, you're paying a premium for more convenient packaging with the PSF over the ATF. I use AFT in my jeeps power steering systems even though the product look up guide recommends PSF.

Amsoil doesn't publish the visc or VI for the PSF. It makes it harder to figure in likely apparent differences in performance at temp.

 

[StevieC]

I dunno the Amsoil PSF works great for me and I find a slight difference over the ATF I was using previously.

I'm stickin' with it for now...

Thanks for the info Gary....

 

[JTK]

Try to find PSF-4. I can't even find PSF-3 for cryin' out loud!! Blasted PSF.. I say a good quality ATF for'em all! It's just a stupid hydraulic pump with a double acting ram? Like Gary says, what could possibly be special in there?!?

Joel

 

[ryland]

Originally Posted By: Gary Allan

Amsoil doesn't publish the visc or VI for the PSF. It makes it harder to figure in likely apparent differences in performance at temp.


The only visc numbers I can find look like the old amsoil atf formulation to me?

http://www.amsoil.com/msds/psf.pdf

Its 7.3 at 100C and 32.2 at 40C

So I guess its slightly thicker than the old formulation and only .3 off of the new at 100C and 6.7 off at 40c.

I have a quart of the old atf in my garage I dont know what the visc numbers were for that but I bet they are pretty close to the PSF.

 

[Tremo]

Yep, a PS system is just a hydraulic pump and a ram. Doesn't really need all the adds and friction modifiers of ATF.

RL PSF is red tinted like ATF but not as deeply. Valvoline PSF is clear.

 

[Gary Allan]

Viscosity, cSt @ 100C ........................................................................ 7.30 Viscosity, cSt @ 40C .......................................................................... 32.2 Viscosity Index ...................................................................................... 204

Yeah, I never had to look at the MSDS to get the visc numbers. This is the first time the didn't publish them on the product page.