How do you change hydraulic oil in a forklift?

To change hydraulic oil in a forklift, start by ensuring the forklift is on a level surface and the engine is off. Locate the hydraulic reservoir and remove the fill cap, then drain the old oil by opening the drain plug or using a pump. Once drained, replace the drain plug, refill the reservoir with the new hydraulic oil to the recommended level, and check for leaks. Finally, run the forklift briefly to circulate the new oil, and check the fluid level again, adding more oil if necessary.