Just had my 2004 Carrera 4S serviced today. Got home and was reading the invoice and noticed that they put 5-50 Mobil (peak life) oil in my car. The pervious services that the same porsche garage has used 0-40 Mobil oil. Does anyone know why they might have done this, before I call them in the morning. The car is low mileage with only 36000 on the clock, if that makes any difference.