Hello Ken, sepulchrave. Thank you for your answer.
Ken last service was 4k km ago and was the 210k km one, so fuel filter change was in the list.
Sepulchrave I live in Athens, Greece, so temp isn't very low (tomorrow it'll be 13-21 oC) and the first time I had the problem was about a month ago with temperatures up to 30oC. It is a new hint though and I'll try to check it. Thank you again.
The only unusual thing is that after a water pump change a year ago I'm adding about 1/2 lt of water every month or so without any obvious leakage (drops at the floor, or white stains during oil change, or water in the cabin etc.).
