In general, engine oil has a shelf life of around three to five years if it has been stored properly in a cool and dry place, away from direct sunlight and extreme temperatures. However, it's important to note that the specific shelf life and recommended usage duration can vary between different oil brands and formulations.
In the case of the Motul 15W50 engine oil you mentioned, it's always best to refer to the manufacturer's recommendations and guidelines. The oil container or the manufacturer's website should provide information regarding the shelf life and recommended usage duration for their product.
If the oil is still sealed and has been stored properly, it may still be usable. However, if the oil has been opened or has exceeded its recommended shelf life, it's generally not advisable to use it, as the oil's performance and lubricating properties may have deteriorated over time.
To ensure optimal performance and protection for your Yamaha FZ motorcycle, it's generally recommended to use engine oil that is within its recommended shelf life and matches the specifications provided by the manufacturer. If you have any doubts or concerns, it's best to consult with a qualified mechanic or contact the oil manufacturer directly for specific advice regarding their product.