This video demonstrates how to perform a complete hydraulic service on a commercial zero turn with hydro-gear hydraulic pumps. Most manufactures recommend this to be done between the first 250 and 400 hours of use. After that every 400 hours this should be done. It includes replacing the filters with OEM Hydro-Gear Parts and changing the hydraulic oil. In this case the recommended oil would be Toro's Hyper 500. The more often you service the hydro's the longer they will last. If you neglect the them it can lead to catastrophic failure which can cost into the thousands to repair.