hydraulic oil question

glennster · Oct 20, 2014

ok so i have this old prime mover skidsteer, vintage 1982. previous owner was running hy-tran hydraulic fluid in it. i am replacing one of the drive motors new. trw-ross motor. main pump is a sunstrand sauer. the owners manual (finally found one) said to use 10w40 se/sf rated motor oil. it is an old rating. guy at the hydraulic shop recommended i run 10w40 motor oil mixed 50/50 with dextron 3 transmission fluid. he said the trans fluid will add anti foaming and anti wear additives to the oil. any thoughts????

old · Oct 20, 2014

I would say that would be just fine. Seen more then one machine that called for ATF as hyd fluid

Wile E · Oct 20, 2014

What type of pump is the Sunstrand Sauer unit?

Gear, Piston, Vane?
I would not normally argue with the owners manual, but I would think that a lighter viscosity would be needed for a hydraulic system.

glennster · Oct 20, 2014

the pump is a variable displacement axial piston pump .

Bob Bancroft · Oct 20, 2014

I worked at a NH dealer when they introduced their skid-steers. I can't remember the progression, but they, at different times, recommended ATF, trans/hyd. oil, and motor oil.
Before the days of trans/hyd. oil AC recommended motor oil in a tractor where the hyd. was a common sump with some gearing. I recall some new tractors coming from the factory with ATF in a similar situation. Then came trans/hyd. oil, which seems to work fine for many manufacturers and applications. I would keep it simple and stick with it.

Wile E · Oct 20, 2014

Hmmmm, Yep. In that case I would do what the owners manual says. I still think that 10w 40 is too thick for a hydro system.

In the hydro-static drive on my diesel compact I use low viscosity Hy-gard. The parts guy at the dealer specifically said to me....."Do you use your tractor in the winter" You bet I said. Ok then he said I will pull a pail of low viscosity Hy-gard for you......That will be $75 or whatever it costs. Hygard should be thinner than 10w40.

David G · Oct 20, 2014

I would check out the high viscosity hydrostat oil that deere uses in there small tractors.

Geo-TH,In · Oct 20, 2014

I have a 2004 Terramite T5C. It has a twr pump, not sure of hydro motor. IN BOLD PRINT IT SAYS ONLY USE 10W40, not hyd fluid. Hydro fluid will cause damage. I have a little over 1500 hours on it. Cange Hyd fluid every 300 hrs with 10w40 as recommended, change filter too. So far so good. Had to rebuild 3 of the 10 cylinders, no other issues.

Jack345 · Oct 20, 2014

I have a Sunstrand Transmission and 10w30 or 10w40 is recommended and has worked just fine since 1977. Also the owners manual for my Ferris zero recommends Mobil 1 for drive motors.

Check Break · Oct 20, 2014

We used to run 30wt engine oil in all our Caterpillar powershifts as that was the spec called for when they were made in the late 70-s and early 80-s. If you use that same 30wt today, you'll be replacing transmissions. All the oil formulas have changed due to the new emission requirements. This topic generates a lot of diverse opinions. If you want the engineer's perspective from one who is extremely qualified in this area, go down to Crawlers, Dozers, Loaders and post up the same question for Old Magnet. He can get you headed in the right direction. I would not use current spec 10-40w until I determined what the new additives would do to the hydraulic system.

T in NE · Oct 26, 2014

Probably because ATF is essentially a hydraulic fluid.

hydraulic oil question

glennster

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old

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Wile E

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glennster

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Bob Bancroft

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Wile E

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David G

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Geo-TH,In

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Jack345

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Check Break

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T in NE

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