* October synthetic quoted at $13.25/bbl over WTI
* Syncrude unit outage means 500,000 bbl cut in Sept
* WCS quoted at $9/bbl under WTI
CALGARY, Alberta, Sept 13 (Reuters) - Canadian synthetic crude prices eased on Thursday as it became apparent an outage of some equipment at Syncrude Canada Ltd would have a relatively modest impact on output.
Light synthetic for October delivery last sold for $13.25 a barrel over benchmark West Texas Intermediate, down $1.50 a barrel from Wednesday, according to Shorcan Energy Brokers.
Syncrude Canada, one of the largest two Northern Alberta oil sands miners and processors, had taken a steam generator at its Aurora mine down for repairs in a move that will mean the reduction of 500,000 barrels of output in September, a source familiar with operations said.
A 20-day outage would mean average reduction of 25,000 barrels a day this month, for instance, though it is not known when the unit, in the separation of bitumen from sand, went off line or when it will restart.
Canadian Oil Sands Ltd, which has the largest stake in Syncrude and speaks about operational issues for the partnership, has declined to comment on outage.
Syncrude produced 359,500 barrels a day in August.
The market was already tight with Suncor Energy Inc having started a six-week turnaround on a vacuum tower at one of its upgraders that will include work on a coker unit .
Heavy crude prices strengthened, meanwhile. Western Canada Select heavy blend for October was quoted at $9 a barrel under WTI, compared with $9.50 on Wednesday.