Okay, so I've been chasing my tail on this for a bit to the point that I'm almost ready to redesign the hydraulic system, but I think I may just have an issue with the fluid now that we're getting summer temps here. I've got a tractor that calls for the Kubota UDP fluid. It's a rebadged L245DT that Kioti sold as one of their first models in '86. Both tractors originally called for SAE 80, then the spec was updated to UDP by Kubota, which I believe is an SAE 20/ISO-68 oil. Kioti does not support these tractors any longer, so no input from them on what to use now. When I put the above mentioned VP J20A in, which claims UDP compatibility, the system won't work at cold temps, either very slow at sub-60*F, or when at freezing temps, it won't work at all. When it warms up, function is fine, but in very cold weather this can take several minutes before the loader will even budge. Noted on the tractor supply website they say it is an SAE 20 or ISO-68 viscosity, so that checks out vs. the old school UDP. I would think that this should have better cold weather flow performance than an SAE 80 oil, but based on some reading I've been doing here, maybe not?
I still haven't ruled out that this is just a poorly designed hydraulic system. The little hydraulic pump driven off the back of the injection pump powers the rear lift, the loader, and the steering. Steering is supplied through a priority valve before anything else gets fluid. The hydraulic fluid is shared with the gearbox. The steering works 100% of the time perfect, even when cold. It's just the loader and 3 point lift that take a while to respond when cold. Do you think a multi-viscosity oil like a JD J20C or the lighter Kubota UDT2 spec would fix this issue? I think the J20C is 10w-30 and UDT2 is AW-32/SAE 10. Thanks in advance for any insight. It's working fine for now with the warm weather, but I'd like to have this sorted by this coming fall.
I still haven't ruled out that this is just a poorly designed hydraulic system. The little hydraulic pump driven off the back of the injection pump powers the rear lift, the loader, and the steering. Steering is supplied through a priority valve before anything else gets fluid. The hydraulic fluid is shared with the gearbox. The steering works 100% of the time perfect, even when cold. It's just the loader and 3 point lift that take a while to respond when cold. Do you think a multi-viscosity oil like a JD J20C or the lighter Kubota UDT2 spec would fix this issue? I think the J20C is 10w-30 and UDT2 is AW-32/SAE 10. Thanks in advance for any insight. It's working fine for now with the warm weather, but I'd like to have this sorted by this coming fall.