I realize this is a slightly older post but someone pretty much hit the nail on the head. This is a non commercial engine on a non commercial very budget friendly piece of equipment with a life rating of 115 hours. The oil change interval if it had one would have been 100 hours. Considering the engine would likely be worn out in 15 more hours what would be the point of changing the oil? Nothing says you aren't allowed to change it. You can change it every 5 hours if you want to. There is no drain plug which is pretty common these days and the suggested method of draining the old oil on longer life engines similar to this one is to tip the mower so the oil will drain out of the fill tube.
