I noticed Mercedes has switched to the 0w-30 for my SLK32. The dealer changed the oil for the past 4 years as a freebee. About two years ago, they switched to the above viscosity from a heavier oil.

I only use the synthetic stuff in my track car. Now that the freebees for my SLK32 are over, I may go back to dino oil in it when I change it.