Never put anything other than diesel into the diesel tanks of Trigger's Brush or my current MKII Octy, never failed on emissions. Maybe yis aren't maintaining them properly? I change the oil and filter every 20k kilos (well ahead of dynamic schedule) and the air and fuel filters every 90k kilos (in accordance with manufacturer recommendations). I replace the pollen filter every 40k kilos (recommended = 60k) because I tend to leave the cabin air blower on low all the time.
