* October synthetic trades at $0.90/bbl below WTI
* October WCS trades at $25.70/bbl below WTI
CALGARY, Alberta, Sept 4 (Reuters) - Canadian synthetic crude price strengthened on Wednesday as Suncor Energy Inc began planned maintenance work on one of its oil sands upgraders near Fort McMurray, Alberta.
Light synthetic crude from the oil sands last traded at a 90 cent discount per barrel to the West Texas Intermediate benchmark, according to Shorcan Energy Brokers, compared with a settlement price on Tuesday of $1.10 below WTI.
Suncor, Canada's largest oil company, said it has started a work on the vacuum unit at its U2 oil sands upgrader, which converts mined bitumen into refinery-ready synthetic crude.
The company said the 240,000 barrel per day unit would be partially closed for up to five weeks while the 100,000 bpd U1 unit would operate normally.
The upgrader is one of two scheduled for maintenance this month. Husky Energy Inc is expected to stage a 45-day maintenance turnaround at its 82,000 bpd heavy oil upgrader in Lloydminster, Saskatchewan.
Canadian heavy oil prices slipped. Western Canada Select heavy blend for October delivery last traded at a discount of $25.70 per barrel under WTI compared with the day-prior settlement price of $25.25 per barrel below the benchmark.