had the injectors replaced on monday, followed it home no black smoke washed car on tuesday, No black soot on rear of car and it has been driven all week about 25ks a day, soot would previously appear after about a 10k drive. Soot would leave a dusty residue on your finger when you wipe the back of car definately not oily. Soot appeared on rear of car from the first day we picked it up, and yes it does use oil, so far 3l at 6000ks