Yes, according to another post on this website the 0W-30, 5W-30 and 10W-30 Mobil 1 oils are NOT true synthetics in that they start with dino oil as the base oil and MB does NOT approve these viscosities of Mobil 1. You should also know that MB does not approve the 15W-50 Mobil 1 either although it is a true synthetic but I assume these are fuel mileage issues. Who would have thought that non-synthetic anything could be marketed as synthetic? Wacky.