Pulsar 150cc 2020 – Oil Change Interval, Time & Best Engine Oil?

Hi,

I ride a Pulsar 150cc 2020 model. The manual says to change oil every 10,000 km, but my mechanic insists on 2,500 km. My friend says change it for every 3000kms. How often do you change your oil, and what's worked best for you? How often should I change it in months, if I ride less? I mostly ride in city traffic.

Also, what's the best engine oil for this bike

Thanks!