If the Mx5100HST is like my L3400HST, and I bet it is, you will need for your 50 hour change the Hydrostat filter, the Hydraulic filter and an Oil filter, your engine oil, and a quart or 2 of SUDT to make up for any spilled when you change the hydro and Hydraulic filters. Also calls for chassis greasing several zerks. You dont change out the SUDT Hydraulic/hydro oil until 400 hours. Now I know some guys do actually change out Hydraulic oil at 50, it is up to you, but I am going by what the manual says to do. it is not real hard, dont forget the oil pan (at least on mine) has 2 drain plugs, check your manual, but The SUDT is the same in it now as what you would put in it.. there is no mention of "break in fluid". Good luck
James K0UA