The best engine oil for your FZ Fi version 2.0 can be inquired from the authorized Yamaha service center. The engine oil capacity of the motorcycle is 1.2 liters and their are many brands selling the same category of engine oils at different prices. You should go for the one chosen by the service center as they always keep a balance between performance and efficiency of a motorcycle. A wrong quality of engine oil can ruin your engine's life and decrease the quality of performance being delivered by the motorcycle. The FZ Fi has a service interval of 6000 km, making it quite a long stretch as compared to Hero's service intervals of 3000. This is the result of added Fi and the better quality of engine oil for the FZ Fi. It keeps the bike smooth and sludge free for a long period of time.