I have a feeling that it is sort of the nature of the beast because it seems like most all 6 cylinders have the same problem. I also have a 420sel with the v8 and it does not use a drop(knock on wood). It also seems to be that the 6's do not have quite enough power to pull that heavy of a car. I did, under ok from my MB mechanic, use the Lucas oil stabilizer and it seems like the initial starts are a little rough, but the acceleration from a stop light seems to be much better and smoother. It used to almost have to go into high(passing) gear to pick up decent speed from a stop light. Now, you don't have to kick it as hard. But, it seems like the oil consumption is still just about as much as it was before the Lucas. So, I don't know. My MB mechanic is puzzled by this.