Chennai is 3.5 hours ahead of Oslo

Best overlap: 8:30 AM to 2:30 PM in Oslo is 12:00 PM to 6:00 PM in Chennai.

For the smoothest call, aim inside 8:30 AM to 2:30 PM in Oslo, i.e. 12:00 PM to 6:00 PM in Chennai. The overlap is wide at 6 hours, so you can protect mornings for deep work and still find plenty of meeting time. Daylight saving complicates things slightly: Oslo observes it, Chennai doesn't, so the difference flexes by an hour part of the year.