Экспорт данных из DataGrid в Excel с указанием кодировки

dataGrid1.SelectAllCells();
                dataGrid1.ClipboardCopyMode = DataGridClipboardCopyMode.IncludeHeader;
                ApplicationCommands.Copy.Execute(null, dataGrid1);
                String resultat = (string)Clipboard.GetData(DataFormats.CommaSeparatedValue);
                String result = (string)Clipboard.GetData(DataFormats.Text);
                dataGrid1.UnselectAllCells();
                StreamWriter file = new StreamWriter(@"C:\test.xls", true, Encoding.GetEncoding(1251)); 
                file.WriteLine(result.Replace(',', ' '));
                file.Close();
                MessageBox.Show("Exporting DataGrid data to Excel file created");

StreamWriter file = new StreamWriter(@"C:\test.xls", true, Encoding.GetEncoding(1251));

StreamWriter file = new StreamWriter(@"C:\test.xls",  Encoding.UTF8);

StreamWriter file = new StreamWriter(@"C:\test.xls");

StreamWriter file = new StreamWriter(@"C:\test.xls", true, Encoding.UTF8);