old debate: Power Steering Fluid or ATF for power steering system

[MrRPM]

jeep wranglers say not to use ATF in the manual but then in 2003-06 the manual says to use ATF +4 even though i don't think there are any changes.

my system was just changed at the dealer since I had a gear box replaced and the fluid seems to be PSF since its not red like the atf is

 

[widman]

Originally Posted By: widman
A couple of days ago I posed this question to a formulator at a blending plant where both are made. This was his response about the power steering fluid:

This is basically a multigrade hydraulic fluid with seal swell additive.

The cheaper ones on the market are just base oil plus seal swell.

Regards,


I posted that last night without comment as I was drawn away from the computer. My interpretation of that statement is:

Brands that specify a particular PS fluid want to make sure it meet minimums.
When you can buy PSF that is base oil with seal swell, you have no AW to protect, and little VI

When you just go with a basic hydraulic fluid with seal swell, you have a little AW plus the added VI range.

When you go to a specific spec, you might get higher AW, or something added like anti-foam, etc.

In an ATF, you have seal swell, high VI, high detergency that I believe will keep valves cleaner, better pumpability in cold, better anti-foam, etc.

 

[MolaKule]

Quote:
Brands that specify a particular PS fluid want to make sure it meet minimums.


I think it's more complex than that.

All hydraulic fluids, whether simple or complex, have seal swell addtives. This formulator makes it sound like hydraulic fluids have seal swell additives added after-the-fact.

One of the reasons GM has specified their latest version of power steering fluid was to have a good AW/anti-oxidant fluid with low metallic detergency and have the same viscosity of about 7.3 cSt.

I can tell you, there are many different formulations of ATF's and power steering fluid's. But the original Honda Power Steering Fluid is very close in additive content to the Redline power steering fluid.

If I had a Honda, that's what I would use.


For all other vehicles that do NOT allow or spec ATF in their Power Steering systems, I consider the Amsoil power steering fluid and the latest GM power steering fluid to be superior.

 

[atc250r]

Now read this goofy TSB and tell me what you think. I have a '97 Ram and I will be replacing the steering box next week. Do I need to use Mopar 5931 or since I'm completely flushing the system can I change to Amsoil ATF?

http://dodgeram.info/tsb/2003/19-005-03.htm

 

[tommygunn]

Originally Posted By: atc250r
Now read this goofy TSB and tell me what you think. I have a '97 Ram and I will be replacing the steering box next week. Do I need to use Mopar 5931 or since I'm completely flushing the system can I change to Amsoil ATF?

http://dodgeram.info/tsb/2003/19-005-03.htm


Exact same TSB I was referring to with my car, a 97 Stratus.

Honestly, I drained it all and replaced it with ATF+4. It works totally fine. I know there's another TSB which states for alot of 90's era vehicles to change it to ATF+4 for better cold weather performance.

So, that TSB says no, but I did anyhow, never had an issue. No idea about Amsoil stuff, I used a licensed ATF+4, Castrol brand. Hasn't exploded yet.

 

[atc250r]

Originally Posted By: tommygunn

Exact same TSB I was referring to with my car, a 97 Stratus.

Honestly, I drained it all and replaced it with ATF+4. It works totally fine. I know there's another TSB which states for alot of 90's era vehicles to change it to ATF+4 for better cold weather performance.

So, that TSB says no, but I did anyhow, never had an issue. No idea about Amsoil stuff, I used a licensed ATF+4, Castrol brand. Hasn't exploded yet.


Not an easy TSB to understand, that's for sure. I have lots of Amsoil ATF on hand, so I might try that. Just don't want any leaks, or problems.