The Hustler Z is a three-bladed commercial riding lawnmower manufactured by Power Pro Equipment. Its rear drive wheels are hydraulically operated by separate pumps powered by the gasoline engine. These pumps share a common hydraulic oil reservoir and filter. Power Pro recommends checking the hydraulic oil every week or after every 50 hours of operation. Changing the hydraulic filter only is recommended after the initial 50-hour break-in period. Thereafter, the hydraulic oil and filter should be changed annually or after every 500 hours of operation.
Purchase the correct fluid. For the hydraulic reservoir, only SAE 20W50 SG, SF/CC, CD service motor oil is recommended (do not use hydraulic fluid or transmission fluid). The hydraulic oil filter is Hustler part number 768341. Capacity of the hydraulic system is 5 quarts.
Locate the hydraulic oil reservoir in front of the engine, beneath the operator's platform. Set a drain pan underneath the drain plug. Take off the reservoir filler cap and remove the drain plug on the bottom of the reservoir with a combination wrench. Allow oil to drain from the system.
Locate the hydraulic oil filter. It's a spin-on type filter, similar to automotive varieties, located just in front of the hydraulic reservoir. Unscrew the filter with an oil filter wrench.
Smear a small amount of clean oil around the gasket of the hydraulic oil filter, then fill the filter with clean oil. Holding the replacement filter upright to avoid spillage, screw it on the oil filter adaptor by hand until the gasket on the filter makes contact. Tighten another 3/4 to 1 turn.
Replace the reservoir drain plug. Add 20W50 SG, SF/CC, CD service motor oil until the level is one inch from the top of the reservoir. Replace the reservoir fill cap.
Start the engine and throttle up to approximately 2/3 of maximum. Hold that throttle setting for a few minutes to bleed any air out of the hydraulic system before engaging the steering control.
Stop the engine and check for leaks. Add more hydraulic oil to the reservoir as necessary to bring the level to within one inch of the top.