I have a 231S that has 230 hours on it that I bought about a month ago. I don't have a record of it having a 50 hour service check and I was wondering if I should perform a general ALL TRACTOR fluid change with filters? My question would be: when I change the hydraulic filter, will I loose all the fluid and therefore need to completely change and refill with new fluid(and if so, will something other than the Massey Ferguson brand work as well)? Also, what filter number will I need for the hydraulic filter replacement?