Yes, you may use 10W 40 grade engine oil for the Yamaha FZ-S Fi V3. Moreover, you may refer to the user manual of your bike for more details.

It's why most high-mileage motor oils (like Castrol ... Mileage Motor Oil costs $32.47 (it's currently on sale on Amazon for $29.97), while five quarts of Mobil 1 Advanced Full Synthetic 5W ...

I personally prefer Motul 10W40 or 10W50 Synthetic engine oil with Castrol 85W90 Gear oil. It runs smoothly and the instant pickup feels in hand. TVS has it's own brand TVS STRU4 Engine Oil which ...