I have a 98 ML 320 with 49000 miles on it. A few months ago the dealer which services my car suggested that I change to synthetic oil. I took their recommendation and switched over to synthetic. But ever since the switch at 42000 miles the car has been using oil. I have put in 2 1/2 qt of mobil 1 since that time. Iam going back to the dealer next week for another service, should I notify the dealer? Is the oil consumption normal? Thanks for all replies.