Traders in Calgary said market action was relatively subdued on the first trading day after the Christmas and New Year holiday period.

Western Canada Select heavy blend crude for February delivery last traded at $13.65 per barrel below the West Texas Intermediate benchmark, according to Shorcan Energy brokers, down from a settlement last week of $13.40 per barrel below WTI.

Light synthetic crude from the oil sands changed hands at 35 cents per barrel below WTI, sliding from 10 cents per barrel above the benchmark last week.

Canadian Oil Sands Ltd (>> Canadian Oil Sands Ltd), the largest-interest owner in the Syncrude mining and upgrading project, said last month it was advancing a turnaround on one of its cokers at the facility, which is expected to lead to improved production and increased synthetic crude supply in 2016.

(Reporting by Nia Williams; Editing by Lisa Shumaker)