But. I am getting the impression that you don't like all of MB229.51 and MB229.52 spec oils and feel that there are good and bad choices within those same specifications.
You are getting wrong impression.
It is not me, who doesn't like MB229.51/2 formulation but modern diesels and I posted where you can find a proof of that.
FYI I am doing 13,000 miles oil change intervals on MB since 1997. At the time oil quality was dictated by engineers and for several years we used dino oils. That include ML320, who not only is heavy vehicle, but was used a bit for towing 5000 lb trailers and was sold with 130k miles running perfectly. Sludge was never an issue.
When I am new to Sprinters, I notice that the same engine in Sprinter has much bigger oil capacity, what easily extends the intervals.