N12B16A: Engine oiled, jerking in the lower speed range

Hello, I took over the R56 with 153 tkm, meanwhile it has 175 tkm. I took over it apparently after fresh engine wash, because in the course of time he has oiled himself nicely, so that in the warm condition after the ride also front left a few times dripping. In the stand with warm engine it smells also clearly by the ventilation in the interior. The free workshop first noticed a loose screw on the oil tank and as a cause, but it was not. They could not make a more accurate diagnosis yet, but also suggested a motor wash and then observation. Oil consumption quite high, due to a lot of short distance and always a little refilling again I did not measure it more accurately. I first noticed this after a few thousand km, when the engine at the traffic light simply went out. No warning lamp was on. There I noticed strongly that proper oil is missing and since then still observed/replenished. In the forum search I first pushed on it that I will replace the 5W30 by 10W40. In addition, the Refreshing is said about 10 times.