I just use DELO 15W40 from Wal-Mart, it has excellent soot dispersion and detergent properties. In fact, I developed a few small oil seeps and started burning oil from the valve seals in my 300E afer a few oil changes with this oil, which tells me it has cleared some solids. Yet it is gentle compared to aggressive engine flushes.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280