One of the strong points of all of our 190's is that the engine is happy with regular motor oil. There are no weak points in our engines that need synthetic oil to help band-aid design problems. Go on the Saab sites and read about sludging. They need synthetic to band-aid a poor PVC system. Some BMW M-3's need special 60wt type oil to band-aid undersize conecting rod dimentions. We drive small "tanks" that were over designed and slightly underpowered. If I would run synthetic, I still would choose a heavier oil like Mobil 1, 15-50. I would only run 5-30 in my car if the temperature never got above freezing. I ran straight 30 wt. Shell ($0.59) a qt. and sent an oil anylasis out for testing and the lab said the oil was so good after 3,000 miles that I could sell the oil to my neighbors! So, put in whatever you want and use a quality filter. The timing chain likes clean oil so just following the recomended oil change interval in the owners manual is fine. Just my opinion.....The owners book has a great chart in it for viscosity.