I just answered a post regarding oil consumption on a 420SEL. Now my question is this, my car is consuming about 1.5 quarts every 1000 miles or so... I only notice a blue smoke when the engine is warm, mainly when I accelerate away from a light after sitting for a minute or two. I do notice more smoke if I sit at the light for a longer period of time, say 3-5 minutes, under the same circumstances - accerleration. Would this be valve seals/guides or worn rings. There is a slight shaking when the engine is at idle, but not very much, used to be no shaking. Performance and fuel mileage have not suffered at all, car still runs and accerlerates well with plenty of power. No noticeable noises from the valve train either. Any suggestions on where to start and how expensive are seals to replace.