* The discount on WCS for January delivery in Hardisty, Alberta, traded between $18.50 and $18.90 a barrel under WTI, according to brokerage CalRock, tightening from a close of $19 a barrel under the U.S. benchmark on Monday.
* Canadian heavy differentials have narrowed in recent sessions, helped by an end to seasonal U.S. refinery maintenance that weighed heavily on demand, although market players are still concerned about potential delays to the 590,000 barrel-per-day Trans Mountain expansion project.
* Global benchmark oil prices fell more than 3% to their lowest level in six months on concerns of oversupply and after U.S. economic data showed an unexpected rise in consumer prices.
* The outright price of WCS was just over $50 a barrel.
(Reporting by Nia Williams in British Columbia; Editing by Sherry Jacob-Phillips)