Since its purchase five months ago my signficant other has added 20,000 miles to the odometer. The vehicle averages about 1000 miles per week usually with one long journey of around 700 miles and ten or so short journeys of 30 miles. I have read about the problems with dinosaur oil an ML engines and have been using Mobile 1 15W50 since acquiring the vehicle. To date, I have changed the oil and filter three times with 7k miles between changes. The deposits have only occurred recently with the onset of colder weather. I did hear from one other ML owner who experienced the same problem but after switching to synthetic Mobil 1 0W40, the problem has not re-occurred. Perhaps it is advisable to use 0W40 for the winter months?