Funny , but my 190E 2.3 started to tick for a few seconds on start-up after the last dealer service. This was after the car was changed over to Synthetic oil.
In Australia the dealers now put Mobil 1 (5W - 50) in every car they service. I asked for normal Dino oil at the last service and they said that they don't have any.
Think I might drain it out and put the old Castrol GTX (20W- 50) back in !!