Change to different Hydraulic fluid

   / Change to different Hydraulic fluid #1  

3Ts

Elite Member
Joined
May 27, 2017
Messages
2,656
Location
East Texas
Tractor
Case, Kubota, John Deere
I have a 10hp Case tractor (model 210) about 1970's vintage that calls for SAE 30 motor oil for it's hydraulic system. (It has a gas engine driving a hydraulic pump which then runs a hydraulic motor on the axle and a hydraulic cylinder for the hitch.) I also have a Kubota L235 that calls for Kubota UDT hydraulic fluid for its transmission and hydraulic fluid. I am about to get an implement that will be used with both tractors and I don't want to have cross contamination of the hydraulic fluids. So I plan to drain the SAE 30 from the Case and replace it with the Kubota UDT (or equivalent). I expect a couple of flushes to get rid of the SAE 30 oil. The question I have is: Will replacing the SAE 30 with the UDT fluid cause any problems? i.e. is viscosity the same, are the additives similar, I'd prefer not to damage the pump or motor in this tractor. They've not been made for many many years so parts are unlikely to be available.
 
   / Change to different Hydraulic fluid #2  
Why mess with what has worked for 50+ years? You're just asking for trouble.

I'd leave the Case alone on 30W. Use the new implement on just one tractor and match fluid with the tractor's fluid.
 
   / Change to different Hydraulic fluid
  • Thread Starter
#3  
I kinda figured that might be the situation. I took a closer look at the older hydraulics and cleaning it out probably can't be done reasonably, so I decided, that if I have to use with both tractors, I can just change out the hydraulic cylinder & hoses. It's a 2x10 so not difficult to do.
 
   / Change to different Hydraulic fluid #4  
The viscosity of UTD fluids usually runs in the 10-20W range. Since Im not a petroleum engineer I don't know the ins and outs of ball pressure stats for testing viscosity and all that scientific analysis.

For a hydraulic system where the main function is pumping a fluid and building up pressure in a device, rather than keeping two pieces of steel under pressure, separated by an oil film, it seems to me that the lighter fluid would pump easier in cold weather conditions. Since oil doesn't compress, it shouldn't make any difference in the lifting pressures available with your hydraulic system.
 
   / Change to different Hydraulic fluid #5  
Yeah I'd leave it alone. I switched to AMSOIL ATH in all my equipment, but it's newer, and it meets manufacturer specifications. I'd just use what Case said to use and call it a day
 
   / Change to different Hydraulic fluid #6  
Your Kubota UDT is a low end 20w, maybe upper end 10w oil. Way too light for your old tractor. The 30w is, of course, way too heavy for the Kubota.
 
 
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