I have changed mine once and doing again this weekend. You will require 2 quarts of genuine Exmark hydro fluid to top the system off after you replace the filter. Be sure to follow all of the directions in your manual for best results. Also, do yourself a favor and only buy a genuine Exmark filter as they are NOT the same as an oil filter from the local auto parts store. If you have any other questions, just let me know.
Mike