I wouldn't be that much worried about the detergent nature of synthetics. It's a very mild feature that eventually after the repeated adminstration of synthetics make the engine cleaner but it is not going to "Drain-O" your engine. It's not going to dislodge everything in the engine.

Why I don't use all Mobil 1 in my 300E is because it does not have impeccable maintenance as well as a diet of 87 octane gas for 7 years of its life. The burning of the fuel is not 100% and a less accurate air/fuel ratio. The newer 3 valve Benz engines can run 20,000 mile oil changes because they burn fuel cleaner because of their twin-spark design as well as an ignition coil for each cylinder and MAF sensors. Most likely your newly acquired car, does not have this feature. Also my 300E, leaks a lot of oil and I go through a bottle of oil a week. Not only wouldn't it be economical to burn this oil but also I don't have time to contantly by Mobil 6 packs. There's my 2nd 2 cents