I have read a few posts about people finding shavings in the hst trans when changing hyd oil. I serviced my 4100 the other day for the first time and the screen was for all intents and purposes, clean. Of course there was only 50 hours on the tractor but I could not stand it any longer , had to change everything, it was the second time for the engine oil. I know the book tells us differently but I just feel better. The last JD I had lasted over 20 years and is still going.......