using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var source = "product|11111111|name|2006-10-09|code1|code2|product|22222222|name|2006-10-09|code1|code2|product|33333333|name|2011-02-03|code1|code2";

        var cells = source.Split('|');    // or use \t if it's really tabs

        var lines = string.Join("\n", cells.Select((c,i) => new { c, i })

            .GroupBy(x => x.i / 6)

            .Select(x => string.Join("|", x.Select(y => y.c))));

        Console.WriteLine(lines);

    }

}