How do you change the hydraulic oil in a Kubota b7100hst?

To change the hydraulic oil in a Kubota B7100HST, first, ensure the tractor is on a level surface and the engine is off. Remove the hydraulic oil fill cap, then drain the old oil by locating and opening the drain plug underneath the hydraulic reservoir. Once all the old oil has drained, replace the drain plug, refill the reservoir with the appropriate hydraulic oil, and check the oil level using the dipstick. Finally, run the tractor briefly and check for any leaks before replacing the fill cap.