Looking for help/advice.

   / Looking for help/advice. #1  

homey53

Silver Member
Joined
May 12, 2015
Messages
134
Location
Rutland, VT
Tractor
Kubota RTV 900, 2016 Kubota BX25 DBL
I have a 2009 Kubota RTV 900, and I'm currently doing some routine maintenance ie. engine oil and filter change, air filter (inner and outer) cartridges, transmission fluid and filter, engine coolant check and lastly, the hydraulic oil & filter for the bed lift. Since that oil only powers that single lift cylinder (I think?), does that need to be the expensive UDT2 Hydraulic / HST fluid? Or would a regular hydraulic oil suffice, like the Standard UDT hyd fluid. Thanks

Tom
 
   / Looking for help/advice. #2  
I think you could use any universal hydraulic oil. But here's what my manual says.


20220326_100402.jpg
 
   / Looking for help/advice. #3  
I think you are asking: If either SUDT or UDT can be used, why use one over the other?

One answer would be if at very low temperatures the SUDT has a lower viscosity - flows more easily - than the UDT.
If one flows easier than the other then that is the one you want in Vermot winters. Flowing easily means on startup the oil moves faster to lubricate critical close tolerance parts and avoid cavitation inside the hydraulic pump.

I haven't measuredthe low temperature viscosity for myself, and encourage you to do so. Advertising claims and Internet advice are both full of errors - including mine. A couple of canning jars, a deep freeze, a stop watch, and a funnel with a very small neck would probably answer your question. That's pretty much what the ASTM test looks like.

rScotty
 
   / Looking for help/advice. #4  
If you have an HST transmission stick with the Kubota fluid. If you have a manual gear type transmission you may get away with a more generic choice. Be aware that the transmission and the hydraulics probably share the same fluid.
 
   / Looking for help/advice.
  • Thread Starter
#5  
If you have an HST transmission stick with the Kubota fluid. If you have a manual gear type transmission you may get away with a more generic choice. Be aware that the transmission and the hydraulics probably share the same fluid.
On my BX25DLB the Hydraulics and the HST transmission do share the same fluid, but on the RTV900, there are separate resivoirs for each. Thank you for your reply.
 
   / Looking for help/advice.
  • Thread Starter
#6  
I think you could use any universal hydraulic oil. But here's what my manual says.


View attachment 739102
Thanks Richard. I bought my RTV used, and no manuals came with it. I've got to go on line and get an owners manual. Thanks for your reply.
 
   / Looking for help/advice.
  • Thread Starter
#7  
I think you are asking: If either SUDT or UDT can be used, why use one over the other?

One answer would be if at very low temperatures the SUDT has a lower viscosity - flows more easily - than the UDT.
If one flows easier than the other then that is the one you want in Vermot winters. Flowing easily means on startup the oil moves faster to lubricate critical close tolerance parts and avoid cavitation inside the hydraulic pump.

I haven't measuredthe low temperature viscosity for myself, and encourage you to do so. Advertising claims and Internet advice are both full of errors - including mine. A couple of canning jars, a deep freeze, a stop watch, and a funnel with a very small neck would probably answer your question. That's pretty much what the ASTM test looks like.

rScotty
Thanks rScotty. I appreciate your reply.
 
   / Looking for help/advice. #8  
If you have an HST transmission stick with the Kubota fluid. If you have a manual gear type transmission you may get away with a more generic choice. Be aware that the transmission and the hydraulics probably share the same fluid.
The RTVs don't share reservoirs. The hydraulic bed lift has it's own reservoir and pump.
 

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