How often does a chimney need to be swept for oil furnace?

Answer 1

I doubt it has to ever be swept (although a chimney sweep is sure to complain about that statement).

Its flue at worst gets a little soot from the oil burner but it doesn't get the creosote that wood fires send up and that fireplace users always fear from a chimney fire perspective.

Answer 2

Twice a year is a pretty good guidline. We do ours once in the fall before we start using it for heating and then again in the spring after the warm weather comes.