While you *can* use regular motor oil in your lawnmower, it is not recommended. This is because lawnmower engines are designed for small engines and run at a much lower speed than car engines. Regular motor oil is too thick for these engines and can cause them to run inefficiently, or even cause damage.
Instead, it is best to use a lawnmower-specific oil, such as SAE 30 or 10W-30. These oils are designed specifically for small engines and will help your lawnmower run more efficiently and smoothly.
