What had been scheduled as a one-week shutdown for the Massena GM plant will now extend until January 26.
The decision was made during the past week, according to GM Powertrain spokeswoman Sharon Basel.
She said the decision was based on the demands of GM's engine and assembly plants, which she said GM tries to keep "tightly aligned" with supplies.
The Massena plant is scheduled to close for good later in 2009.
