Use 80w90 gear oil unless you have a loader. In that case use a quality tractor hydraulic oil. Level plug is on the right side of the transmission. Look for a bolt head in the middle of the case just behind the diff. lock pedal about half way up the side. You probably have a bad seal in the brake housing. Is not difficult to replace. For parts or manuals call toll free 1-800-609-5110. satohparts.com