I've been using 10W30 Mobil 1 in the C230 for the last couple winters, and have found it good even at -30C. I buy it in "bulk" (5 litre jugs) and last winter on a very cold night checked it for my own "pourability" test in the bottle. It was VERY liquid, and startling compared to the Quaker State dino 5-30. The QS was like molasses and the M1 was very "sloshy." Impressed me.
1998 C230 "Black Betty"