GM PS pump?

[Mad Professor]

1980s GMC PU PS is leaking, the box not the pump.

I don't always have "real" PS fluid on hand. What is better in a pinch, ATF or Ford spec hyd/gear oil? 5-gal of hyd oil is a better deal.....

I've run my 68 Camaro PS on ATF for a long time and it didn't croak......hell I even ran it with no pump when I was young and poor. When I got a pump it still worked fine......

 

[Stem]

ATF is always a go-to for PS fluid. its essentially the same thing, just ATF has detergents.

 

[Canadian farm boy]

Something of that vintage I’d be using DEX III atf without worry.

 

[Mad Professor]

ATF is always a go-to for PS fluid. its essentially the same thing, just ATF has detergents.

next question, is ford spec hyd flyid bad in a pinch?

 

[Stem]

next question, is ford spec hyd flyid bad in a pinch?

as in Ford/NH 134C etc? I don't see where it would hurt it. hell you could probably get away with 10w30 motor oil.

 

[redneckhillbilly]

my memory may or may not be correct, but I think dex merc III and aw 32 are both 10 weight oils.

I use atf in my stuff just because its easier to just have a spare quart of the another of P/S fluid.

 

[Freak007]

my memory may or may not be correct, but I think dex merc III and aw 32 are both 10 weight oils.

I use atf in my stuff just because its easier to just have a spare quart of the another of P/S fluid.

Your memory isn't far off.

A typical Dex III ATF will have a cSt around 35 KV@40°C and 7 KV@100°C, this works out to be roughly the same as a thick 15 or thin 20 weight engine oil.

AW 32 is so named because it has a viscosity of 32 KV@40°C.

Semantics, but a true 10w would have cSt around 4/25, which would be ISO 22

Functionally, a PS system is a hydraulic system, and doesn't really care what you put in it, so long as it is compatible with the seals/bearings. I run ATF in all my power steering systems except the Hondas. Experience tells me there is something in your typical ATF that is not compatible with Honda systems, and the Honda fluid is much cheaper than repairing the pump and rack.

The Saginaw pump in that square body will live a long and happy life on ATF.

 

[Mad Professor]

Your memory isn't far off.

A typical Dex III ATF will have a cSt around 35 KV@40°C and 7 KV@100°C, this works out to be roughly the same as a thick 15 or thin 20 weight engine oil.

AW 32 is so named because it has a viscosity of 32 KV@40°C.

Semantics, but a true 10w would have cSt around 4/25, which would be ISO 22

Functionally, a PS system is a hydraulic system, and doesn't really care what you put in it, so long as it is compatible with the seals/bearings. I run ATF in all my power steering systems except the Hondas. Experience tells me there is something in your typical ATF that is not compatible with Honda systems, and the Honda fluid is much cheaper than repairing the pump and rack.

The Saginaw pump in that square body will live a long and happy life on ATF.

Besides ATF which costs a lot, I refill PS quarts from the 5-gal pail of universal hydraulic fluid I run in my old Ford tractors. I can still find that on sale for ~$50/5-gal.