Since 2005 I drive a Fiesta built 05.’99, 1.8liter diesel 60 hp (without turbo without climate) twice by the TÜV without problems, no oil consumption even no other flaws. The car had a consumption of 5.5liter diesel on 30% city, 60% country road and 10% highway. The problem A colleague tipped something into the tank about 1 liter; the tank was almost empty at the time. I wrote down full fueled km. That means at mileage 202348km I have about 15liter normal diesel Then, until the tank was almost completely empty, as always 30% city, 70% country road but this time about 300km with trailer highway (500kg weight, trailer load increase up to 900kg from Ford is also through at the TÜV). The result: I used 34.28liter for the full tank at the next tank filling and on the tacho stood 765.7km more on it (i.e. instead of 202348km at the beginning now 203114. Gives after Adam RIESE a consumption of 4.5liter per 100km. The next three tank fillings he has done almost the same thing: 4,6l on 100km to 4,8l on 100km. Now, however, after approx. the 10th full tank he catches to go up again with the consumption. The car now has just 214tskm on it and it now swallows measured 5.6 to 5,9 liter/100km without trailer and the same track profile. Question: how can this be? The colleague who had tipped this stuff into the tank is not more in the country and is no longer reachable. If someone knows what that could have been, in front of all things what is good the product. Can someone give me an answer? In the Ford workshop they wanted to know how to do it themselves. But I have a workmate, co-driver who can testify to the whole because we measured and calculated the whole together (for the purpose of cost sharing). Oil, air and oil filters are changed about every 10,000km without if and but. The trailer I had pulled only once was only 3 0cm higher than the car. So if someone can help me, I’d like to have that again if it’s worth it. Thank you in advance…Wolke71