GM has, for its part, has said that the closure of the plant is necessary as it shifts its focus to electric and autonomous vehicles.
"General Motors acknowledged that it could save the Oshawa Assembly Plant, but simply chooses not to, even though it wouldn't hurt the company's bottom line to keep the plant operational until the end of the current contract in 2020", said Dias.
The union confirmed Wednesday's work stoppage following an earlier protest Tuesday.
The meeting came after GM's "accelerated transformation" announcement on November 26, 2018, which would see the Oshawa plant close in 2019.
"I'm furious right now", Dias added.
GM officials said they responded to Unifor proposals from December and invited the union to begin constructive discussions on transition strategies and supports for Oshawa Assembly workers who may elect to either retire or pursue new careers following their work for GM.
"We're looking at tens of thousands of jobs and a direct hit to the GDP", said Unifor president Jerry Dias in a statement.
Speaking in Windsor, Ont. on Tuesday afternoon, Dias said he was "deeply disappointed" by GM's decision to close the Oshawa facility, calling it an example of "corporate greed".
In November, GM announced it would close 5 plants this year, 4 in the United States and this one in Canada. "This is not only about jobs in Oshawa, but Canadians as a nation. That's the only acceptable solution as we stand here today".
"The reality is General Motors will only understand if Canadians push them in the decisions they are making", Dias said. The question is do they have the political will to do so.
Unifor's national auto director Dino Chiodo, former president of Local 444 in Windsor, also expressed his frustration with GM executives following Tuesday's meeting.
"In our history, Chrysler has never approached what GM keeps doing to us time and time again", he said.
The options suggested by the union, including extending the life of the Chevy Impala and Cadillac XTS now produced at the plant or shifting production slated for Mexico to the plant, are not economic, said David Paterson, vice president of corporate affairs at GM Canada.
With the GM world headquarters towers looming in the Detroit background, a billboard message from Unifor on Wyandotte Street East in Windsor, shown January 8, 2019, has a message about the automaker's Oshawa Assembly Plant. One of the plants is the Detroit Hamtramck Poletown plant set to close in July.