UPDATE 1-Unit at Imperial's Sarnia refinery down for weeks

* Maintenance to last for several weeks
* June WCS heavy crude discount widens
* Nanticoke refinery also undergoing upkeep


CALGARY, Alberta, May 8 (Reuters) - Imperial Oil Ltd
has...

Source: http://feeds.reuters.com/~r/news/usmarkets/~3/qln9-O4BSbc/refinery-operations-imperial-idUSL1E8G89M420120508

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