The discount on Canadian heavy crude versus the West Texas Intermediate (WTI) benchmark widened on Tuesday.

Western Canada Select (WCS) heavy blend for May delivery in Hardisty, Alberta, settled at $13.20 a barrel below WTI, according to NE2 Canada Inc, widening from Monday’s settle of $12.20 a barrel under the benchmark.

One industry source said a refiner with upcoming maintenance was selling May barrels.

Light synthetic crude from the oil sands for May delivery settled at $5.45 a barrel over WTI, weakening 40 cents from the previous day.

Canadian crude prices are expected to be supported throughout the second quarter as annual maintenance work in the oil sands shutters roughly 5% of Canada’s crude output, although the decrease in supply will offset to some extent by refinery maintenance reducing demand.

Global benchmark oil prices eased in volatile trade, pressured by a rising U.S. dollar and growing worries that new coronavirus cases could slow demand. However, losses were limited by supply concerns due to sanctions on Russia for alleged war crimes.