There was some recent discussion about splash lubricated B&S OCIs. I like to change mine at 25 hrs (twice a season), and I just reached 25 hrs today. Changed the oil in my 2013 17.5HP 500cc B&S PowerBuilt Intek w/o oil filter running 5W30 Formula Shell Full Synthetic. 48.6 total hours on the engine. Oil was previously changed at the end of last season. Ran the used oil through a #4 coffee filter. Saw nothing in the filter. However: 1) The filter became saturated with some kind of very fine particles, and would not pass the last 1/4 cup of oil. Tried to take a picture, but basically looks like a filter soaked with used oil. 2) I am using a magnetic NPT drain plug, and it had about a 1/16" buildup of very fine metal filings on the tip. I am planning to stick with 25 hr OCIs, because thats my comfort level. But, I can really see no reason not to run the recommended 50 hr OCI. 100 hrs seems to be stretching things, though.