I been working on small engines sents 1989 and I always recomend changing the oil at lease once a year. But also relpaceing air, oil, and fuel filters. SO YOU CAN CHECK THE OIL! LOL
I work at the Fix-it-shop about 10 years and a lady drop off her riding mower and said " It just stop running while I was cutting my one acre yard." She also told me that it has a two year warranty on the engine. So after checking the mower found it had no oil in engine and was lock up. I called the customer and told her it was not warranty. She got mad. I ask her why she didn't check the oil before cutting. She was told by the saleman at the local chain store that it is maintenance free and no maintenance was requried. She complain to the local chain store and they give her a new mower. But she come back to us and I show her how to check and keep her mower in good shape. Now she come back ever year.