At the Dealership (Mercedes) we put in Mobil1 5W40. Generally anything that is "European formula" synthetic, which will be a 0w40 or 5w40 meets or exceeds the ratings that the old M112/3 engines required. Obviously there is a bit of discussion about the diesel 5w40 oils (shell rotella t6, which technically isn't synthetic according to European standards), but usually it'll say "meets VW #...MB#...and BMW#.... Also, most M112/113 motors start to tick either from chain noise or carbon buildup on the valves. I regularly see these engines with 200+k on them even though they've had questionable maintenance. Keep in mind this engine family was used in virtually every MB model from 1998-2004, they're tough.