Mixing Hydraulic fluids

Fri Sep 23, 2011 6:43 pm

I have borrowed a Kubota loader & backhoe ( i have a VERY good friend!!)

One of the lines to a stabilizer was leaking, but it is fixed now. I checked the Hydraulic oil reservoir and it is very low, doesn't even appear on the dipstick. The owners manual says it take 5 gallons of either:
Recommended Oils and Temperature Ranges
Do not mix oil grades or types
SAE Hydraulic
Transmission Fluid - - - - - - - All Temperatures
Type “A” or “F” ATF - - - - - - - All Temperatures
SAE 30-30W - - - - - - - - - - - 90° F and above
SAE 20-20W - - - - - - - - - - - - - - - -35° - 90° F
ASAE 10-10W - - - - - - - - - - -35° F and below

I do not know what fluid is in it now, neither does the owner. My plan was to drain it and change the filter so I could fill with one type of oil. But I got to thinking and now I am concerned that I will never get ALL of the oil out of the pump, lines and cylinders. So what to do?

I do not think that the current fluid is either 30W, 20W or 10W.

Right now, I plan on removing a small amount of the current oil and mixing with a small amount of the Hydraulic oil I bought to see how they get along.

Should I be real concerned with mixing the fluids? Should I disconnect each hose and cylinder to completely drain them?

The backhoe is a Woods BH7500. I have the owners manual, but other than the above info, it doesn't say anything about completely replacing the fluid.

Thanks for any opinions !

Re: Mixing Hydraulic fluids

Sat Sep 24, 2011 5:57 am

It's hard to guess what fluid someone may have put in it, but it would have come from the factory with the Kubota equiv. of Hi Tran. I can't remember what they call it. I'd bet your pretty safe to top it off with such a fluid.

Re: Mixing Hydraulic fluids

Sat Sep 24, 2011 7:59 am

Paul, All transmission fluids (Type A, F and Dextron) are dyed 'Red'' - so you can either rule in or rule out if it is transmission fluid. Hope that this helps you in your decision, NJDale

Re: Mixing Hydraulic fluids

Sat Sep 24, 2011 10:22 am

Which tractor is it? If its a hydrostatic it needs the better grade hydro trans oil as it has to hold up to higher temps. Also on my B21 kubota backhoe it has two hydro filters one under a cover in the center of the tractor and one near the rear tire that on mine had never been changed and had gotten plugged up and collapsed inside.

Billy

Re: Mixing Hydraulic fluids

Sat Sep 24, 2011 10:56 am

cowboy wrote:Which tractor is it? If its a hydrostatic it needs the better grade hydro trans oil as it has to hold up to higher temps.


The tractor is a L2900 hydrostatic, but the woods BH7500 is a completely separate unit that runs off the rear PTO. It has it's own pump and reservoir.

b52c130 wrote:All transmission fluids (Type A, F and Dextron) are dyed 'Red''


Thanks for that tip. The oil was not red at all.

I called a local equipment dealer and bought 5 gallons that they said was compatible with the factory supplied fluid. And I bought a filter also.

Thanks!

Re: Mixing Hydraulic fluids

Fri Oct 14, 2011 6:30 pm

There is a difference between automatic tranny fluid and hydraulic oil. The auto tranny oil is for tranny's with clutch plates and some oils like type A has a very fine grit in it so the clutch plates will grab better. The hydraulic oil seems to be more spongy so with systems like our fcubs with gears in the tranny it maybe better for the gear contact and wear.