Bingo, that's the error, thanks.

Corrected:

  You have: 40 MWh
  You want: tonoil
          * 3.4393809
          / 0.29075
  You have: 3.439 tonoil
  You want: barreloil
          * 23.529405
          / 0.042500012
  You have: 23.529 barrel
  You want: liter
          * 3740.8121
          / 0.00026732164
  You have: 3740/30%
  You want:
          Definition: 12466.667

Or a bit above 12,000 litres. Article was correct.