I've found more important than specific oil type/brand min/synth is just to change the oil when it needs changing. I don't do it by hours run time or months on the calander year. Rather I use a very high tech piece of kit, its called a clean white rag. Pull out dipstick and wipe oil onto rag. Take a serious look at it, it'll tell you everything you need to know. FWIW change the oil & keep a clean sealed air filter & the engine will far outlast near every component on the mower. I've got Hondas that have worn 2 decks (commercial thick alloy ones) several hundred sets of blades, wheels, bushes, handle bars, throttle cables, starter assemblies etc. Don't over think it, just change it before it turns dark black/brown. And if its not starting easily off ONE easy pull...fix it. Clean air, half fresh fuel & oil that's not taken tooo far.