My thoughts are this; I use between sae30 or 10w40, but my mowers are a few years old now and broke in good. My church bought a new ZTR mower with a 24 hp. kawasaki and 60 inch cut. Both the dealer and owners manual recommended sae 30 only in it till around 40 to 50 hours when it is broke in good before changing to a multy-weight or synthetic, otherwise it could likely lead to using or leaking oil. I'm not quite sure what other engine manufactures recommend, but would use the 40 to 50 hour period before changing oil weights or types. I changed the original oil and filter in our kawasaki at 8 hours like recommended and it was black. I also strongly recommend chainging the filter at each oil change - cheap insurance against oil problems. Filters are cheap enough for the number of times per year they are changed. I change mine twice a year and have had no oil related problems at all, and grease everything at the same time. Just my thoughts, take with a grain of salt and use for your thoughts, wants and needs.:biggrin: