Traffic flowing after Sydney oil spill

Traffic has returned to normal after a crane breakdown and large oil spill in Sydney's north.

Westbound traffic on Mona Vale Road at Terrey Hills was backed up more than four kilometres on Wednesday afternoon following the incident, which led to a 100m-long slick.

The Transport Management Centre says the crane has been moved and the oil spill cleaned up but some route 196 and 197 buses remain delayed by up to 30 minutes.