I have an 89 300se and a 90 420sel. The 300se does seem to have a couple or 3 seconds of rattle or rough idling, but once started, I believe it actually runs smoother and seems to have a little more power upon red light starts. I believe the car overall runs better. My 420sel(v8) does not have much rattle upon start up at all and it seems to run better when driving. The Mobil 1 synthetic 0w40 is recommended for the European cars, including the MB. I live in NE TN and the climate does not seem to affect the oil rating. My opinion, you will be just fine and probably will find that your car runs better. I have always used Mobil 1 synthetic in all my cars in the past(even other than mb) and you can generally go longer between oil changes and the internal parts of the motor will last longer. It is high on price, but definately worth it in the long run. I just sold my 93 Nissan Maxima se that had 160k miles on it and it ran at the time of sale exactly like it did when I bought it new. I am a believer.