power stteering fluid or ATF for pwr steering, what's the deal?

[MolaKule]

Some power steering units have clutches in them so special friction modification, supplied by the additives, would help. Some units need an extra dose of anti-foamant (1 to 4 ppm) to decrease foaming in the pump.

For those pumps with no clutches, Dexron III or Mecron fluids should suffice for most applications.

In my GM and Nissan applications, I use Schaeffer's 204S. It's one of those "sleeper" products that does well and has good value.

[ May 01, 2003, 01:28 PM: Message edited by: MolaKule ]

 

[satterfi]

Different kind of pumps need different fluids. I'm not a auto mechanic and don't know what kind of pump is in what.

If I recall correctly vane pumps require better protection than say a gear or lobe pump.

I know that's not a direct answer, I've wondered the same thing.

 

[1 FMF]

what is the difference, technically, between using power steering fluid and ATF in a power steering unit?
I read a lot about power steering pumps calling for various fluids from specific power steering fluid to Mercon or Dexron atf to Type F atf.

For a given power steering unit, why would a "power steering fluid" be better, or called for, over an atf fluid? They're both hydraulic mechanisms using a hydraulic fluid, and the base oil to the fluid is what lubricates the components right?

 

[widman]

There are several threads here that have discussed this in detail. There may be more anti-foam in a power steering fluid than an ATF,l according to some, but I am told by many "experts" that ATF will work fine in all.

 

[Spector]

In all my units that call for Dexron or Mercon ATF I have used synthetic. Only one Ford product has Mercon in the transmisson and Type F in the power steering. Have yet to see one of mine that says power steering fluid only.

 

[Blokey]

Also I think some ATFs contain "seal swelling" agents that can wreak havoc on the P/S hoses on some cars. The fluid has to be compatible with the materials used in the P/S system.

 

[MolaKule]

Blokey,

I have yet to see an ATF in a power steering unit damage any hoses. They both contain about the same amount of seal swell/conditioning ingredients, since they are both closed hydraulic units.

 

[Judd]

I have relpied to this question before and alot of folks tend to have issues with what I say.

First off, I am no engineer on lubricants. I am not a expert. I do work at a plant that builds racks and pumps for several manufacturers. Mostly small cars but we do build a few pumps and racks for some SUVs and performance cars. I work in the QA dept. The pumps we build are the vane type.

We use either Nissan PSF or Dexton ATF depending on what we are doing. During the production testing of the pump, we use ATF or PSF depending on what we have at the time. We have switched a few times in the 9 years I've been there. Don't really know why we switch-most likely cost.

If QA is doing a durability test, we always use the Nissian PSF. During the test, the pump is repeatedly taken to relief pressure. This stalls out the pump and heats the oil up bad. From the MSDS sheets I've looked at, the PSF has a higher flashpoint and it most likely holds up better in the high heat ranges the test requires.

Funny thing is, if you call the individual car manufacturers-they individually will all give the same answer. Use only {their brand PSF}.

I beleive that in alot of cases, ATF will work fine. I've used in in my older GM and Ford vehicles for a long time with no problems at all. On the other hand, if you really beat on your steering system {4 wheeling, road race/open track, and especially AutoX} use the best PSF that is recommended for your car.

In my Firebird, I have flushed it twice in 36K miles. I used Valvaline PSF. I will be going to Redline most likely. I play hard with the Firebird and the oil tends to foam when run hard, also gets pretty hot.

I figure that with a regular car that is driven to the grocery store and back and forth to work, ATF would work fine for most vehicles. Just do some research on your car as some do require different fluids {Honda for example}. JMO.

 

[labman]

Good post Judd. Like to hear from those with real experience. If it ain't broke, don't fix it. I don't remember adding either to my 92 Grand AM, bought new and traded after 180K and ten years. It sounds to me like buying one little PSF bottle to top up a good system might still be worth it. With a chronic leaker, go with the cheaper ATF. Better yet, fix it and refill with PSF.

 

[dagmando]

My mother-in-laws '96 Mazda MX6 V6 requires ATF in the power steering fluid. I always tell the oil change places to NOT check the fluids because they just assume PS requires PS fluid and they always seem to want to add trans fluid after they check it while the car if off.