* November synthetic quoted at $4.25/bbl over WTI
* WCS quoted at $14.65/bbl under WTI
* Shell, Suncor conducting maintenance on units
CALGARY, Alberta, Oct 11 (Reuters) - Canadian cash crude prices weakened on Thursday with some refineries and processing units in Canada and the United States going off line for maintenance.
Light synthetic crude for November deliver last sold for $4.25 a barrel over benchmark West Texas Intermediate, compared with $6 a barrel over WTI on Wednesday, according to Shorcan Energy Brokers.
November Western Canada Select heavy blend was quoted at $14.65 a barrel under WTI, a 40-cent deeper discount than on Wednesday.
Prices have weakened dramatically since the start of the month, when the differentials prompted some shippers to move supplies away from the Cushing, Oklahoma, storage hub as they could not compete with the local prices when transport was factored in.
Royal Dutch Shell Plc
said late Wednesday it was taking an unspecified unit at its Scotford oil sands upgrader down for maintenance.
The 255,000 barrel a day upgrader, located near Edmonton, Alberta, processes bitumen from Shell's Athabasca Oil Sands Project.
Suncor Energy Inc
, meanwhile, is scheduled to start planned maintenance at its 93,000 bpd Commerce City, Colorado, refinery this weekend. One of the crude units is slated to be down,
(Reporting by Jeffrey Jones)
Keywords: MARKET CANCRUDE