Hello! My Dad has a 737 ZTRAK that needs the hydraulic oil changed and new filter.I have 15w40 oil to use and the filter.The manual doesnt supply much info. Is the drain for plastic tank on bottom,and where is filter exactly? Is there any bleeding needed,or just change oil/filter. The tractor is not turning as quickly as it should during some operations,unless its on level ground fluid level is okay. Its time to change oil/filter,and I believe that will make things right! Thank you for your answers and help!