Mixing fluids?

[fruitcakesa]

The prior owner of the M4 071 used Napa premium hydro fluid for all the hydraulic services during the 1800 hrs he owned it with no apparent problems. I have always used Kubota Sudt for service on my other tractors.
Can Sudt be mixed safely with other “compatible” fluids?

 

[EastmanAgParts]

The prior owner of the M4 071 used Napa premium hydro fluid for all the hydraulic services during the 1800 hrs he owned it with no apparent problems. I have always used Kubota Sudt for service on my other tractors.
Can Sudt be mixed safely with other “compatible” fluids?

Nowadays the “industry standard” is equivalent to John Deere J20C. It usually will carry the name “Universal/Premium Tractor Hydraulic/Transmission Fluid.” Any oil that is spec’d out to that spec should mix perfectly fine. I am not familiar with Kubota UDT specifically, but I know that brand does not matter near as much as api specs and viscosity of the fluid. If the specs are the same, they should mix without issue.

 

[Roadworthy]

If the tractor has an HST transmission UDT2 is recommended if you really want to play it safe. If it's a standard transmission a mix should work fine.

 

[big bubba]

If the tractor has an HST transmission UDT2 is recommended if you really want to play it safe. If it's a standard transmission a mix should work fine.

in addition, detachable hyd attachments carry residual hyd oil in the lines (and possible condensation) that should be kept in mind given OP's question, ie possible contamination outside the hyd tractor housing.