Please note, Mercedes now list both synthetic and regular oil of the same weight to have the same service temperature. This means Mercedes believes the new petro based oil is as strong (pressure shear strength) as synthetic. Also no independent testings have been able to show reduced wear with synthetic if oils are changed at recommended intervals. Since most enthusiasts like us change our oil at 2000 to 3500 miles, the benefits of synthetic oil is questionable. I used regular oil on my 500SEL and the internal looks new at 165K.