South Korean refiner, S-Oil, will be shutting its Onsan 600,000 tonne/year group II crude oils refinery in early April for around 25 days. The shutdown coincides with the planned shut down of its crude distillation unit (CDU) and its 28,000 bbl/day No.1 vacuum distillation unit (VDU) at its 565,000 bbl/day Onsan refinery in April this year. Another 600,000 tonne/year group III base oils refinery is expected to continue operating during the period.