1 l oel on 6000km????

hiho, unfortunately had to find out that with ttc225 (bj 2001) within the last 6000km of ONE liter oil used. since I only have the vehicle since just this 6000km, I can of course not say if it had been like this before. km was now about 43000. at the friendly, at which I had bought the ttc, they told me that such a consumption would be normal. I can hardly believe that. I have already had some vehicles, tdi and also gasoline turbo, but so much oil have the self m it does not consume 190.000 km. oil stains under the car I did not. because the oil is not exactly cheap and also from o. g. gruenden I would like to know whether this is really soo normal or what it could be. thank you already