When selecting engine oil for your Yamaha FZ-S, ensure that it meets the required performance standards specified by Yamaha. Commonly recommended standards include API (American Petroleum Institute) classification such as API SJ, SL, SM, or SN.
It's worth noting that manufacturers may update their recommendations or specifications over time, so it's always a good idea to consult the owner's manual or contact a Yamaha dealer for the most up-to-date and accurate information regarding the suitable engine oil for your specific model and year of the Yamaha FZ-S.