RIO DE JANEIRO -  Brazil’s largest oil-workers’ union advised Petroleo Brasileiro SA that it plans to begin a open-ended strike against the state-run oil company starting at midnight (0300 GMT) on Friday. The strike is in protest at a recent cut of about 40 percent in investments by Petrobras, as the company is commonly known, and the planned sale of about $15.1 billion of assets, the union, known as FUP, said in a statement on Tuesday. The strike will affect all operational and administrative units of Petrobras including the fuel and oil import and export terminals of Transpetro, the company’s shipping and gas pipeline unit. Officials at Petrobras were not immediately available to comment.