This thing is like a tank compared to my very faithful Woods 6180. I read that after break-in you change oil every 100 hours. Do you guys really wait 100 hrs? I guess i'm old school, I'll change at 50 hrs.. most, the oil is the life of the engine. What replacement oil filter do you use.. such as Fram 3614 ect? Need cross ref. for Kohler. I mowed once and am very impressed, it's built solid.