I have run DELO 400 LE (15W-40) in my E320 for the past 4-5 years with no problems. I use 2,000 mile OCIs. Generally I have used Mann and Hengst oil filters.

The cleanliness inside my engine, with 201K on it at the rebuild, shown in my photos speaks for itself.

Seafoam and other engine "cleaners" are NOT needed with any MB engine. I am not a fan of any sort of additive to MB engines save for things like RedLine Water Wetter (if needed) and the like. If you use Chevron gasoline with any regularity, even good additives like Techron are unnecessary.

Cheers,
Gerry