Attached is a Kioti chart previously posted by another member showing fluids. There has been much member debate on dino or synthetic oil for the engine along with the weight of the oil and OEM or after market filters with I guess no conclusions. Just make sure the oil is rated for diesel engines. I don't think anyone has lost an engine because of a particular diesel oil. Doing the service close to the time schedule is more important for longevity. Hydro fluid debate is not as bad.
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If you have a tractor supply center near you, members posted having good results with the TSC premiun universal tractor fluid that is rated for transmissions, differentials, wet brakes, and hydraulics. You need an oil that works with all these sections. The original Kioti fluid is a 10w-30 multi weight fluid. I just use oem filters that are unfortunately only available from a Kioti dealer, order via internet if no dealers close, or have seen them on ebay. Aftermarket air, fuel and engine filters are easy to find after cross-referenced. NAPA is an easy start to cross. Hydro and hst filters are a little harder and sometimes not at all.
I don't think you can go wrong with any oils as long as it meets specs.