Which power steering fluid do I use?

[jmlcolorado]

Hydroboost from a 1990 Chevy K3500
Power steering pump from an 80's Chevy p30 step ban with 4bt cummins.
Power steering gear from a 79 Chevy c10.

Does it matter what fluid I use?
I haven't looked into each of these to see what each requires yet.

 

[zzrodder]

I've used specific power steering fluid from parts stores and just plain hydraulic fluid too - never seen there to be an issue. It's really just a pump and fluid driven motor or cylinder in the case of rack and pinion so it shouldn't matter, especially when you are combining components from different manufacturers.
Someone please educate me if I'm wrong [S

 

[jmlcolorado]

I'm tempt d to use ATF 4, since the trans takes that anyways.
I'm not seeing anything saying NOT to do that.

 

[Old Iron]

I was told once not to use ATF said it would mess with the seals.
I've always used power steering fluid because of that.

 

[hankthebigdog]

They actually make power steering fluid? I alwys thought atf dexron was the go to. . Just kidding always used atf though.

 

[Perfectly Flaw'd]

I have seen first hand that ATF in newer pumps, etc will cause seal problems. And that was on more than just one car. I use to work for a fleet service and saw this with a few different Chevy pickups.

If it was mine I'd just use power steering fluid, but that's just me.......

 

[Bamamav]

10W hydraulic oil. Shouldn't mess with the seals and be thin enough to flow good. I've heard some folks run it in automatic transmissions, never tried it myself. I have ran 10W40 in the semi's power steering with no problems.

 

[akatao]

a lot the semis use engine oil I like power steering fluid if available if not atf

 

[BlueNorther]

at NAPA we sell 2 kinds of P/S fluid,

one is labelled for Honda/Acura cars and trucks only,

and the other one is for every other car or truck on the road.

newer ATF's have modifiers and seal protectors that will destroy P/S seals.