'lifetime oil' ? WOW ! so no point in any oil changing because the engine will fail due to it's cheap construction/low quality before the 1st oil fill 'wears out' anyway?
Whatever the exact terminology they use, this is how B&S pitches at least their push mower sized engines. Just check and add oil, and they claim you never "need" to change it(even though I do). I think I've seen the specs that they consider "lifetime" 150 hours, which is probably 4-5 years for most people.
As I said, with the one I'm dealing with, there's nothing wrong with the engine but the deck it's on is rotting. That's probably not unusual that the engine outlives the deck, in which case they don't really have any motivation to make the engine last longer.
Most people aren't on BITOG, though. I'd not be surprised if I'm the only person on my block who's changed the oil in a push mower in the time I've lived here. My FIL has an MTD with a Honda engine that he use to have tuned up and have the oil changed annually, although I now do all of that for him(and he went a few years without it at all when the mower shop he used closed). A lot of mowers probably go their entire life without having a single oil change...
Of course as long as I can keep my Lawn Boys running, I'll hopefully never change the oil in a push mower again, but that's a bit of a different story.