General Motors Co. will add a second shift at its Oshawa, ON, Canada, assembly plant in preparation for the launch of its new Buick Regal sedan.

The second shift will be up and running in the fourth quarter, just ahead of Job One for the Regal, expected in first-quarter 2011. Initially, the Regal will be imported from GM’s Russelsheim, Germany, plant until North American output is under way.

The move will allow up to 700 idled workers to return to the plant.

GM says the Oshawa announcement is the latest in a string of “positive” plant actions in Ontario.

The list includes operation of Saturday overtime shifts since June at its Camaro plant in Oshawa, where output of a convertible version of the sports coupe will be added in first-quarter 2011.

The auto maker also has made several moves to expand capacity for Chevrolet Equinox/GMC Terrain cross/utility vehicles in Ingersoll, the latest calling for a $5.7 million investment.

In addition, GM is boosting capacity at its St. Catharines plant to increase V-6 engine production and launch a new 6-speed front-drive transmission.