I've toyed with the idea of running R&P for a single 3k oci in my E350, but since I've recently learned that Valvoline is saying that it takes 4 oil changes to get the full benefit, I'm not sure I want to try it. I'm not keen on the idea of running an oil that isn't MB certified, for 4 consecutive oil changes.
I have also toyed with the idea of trying an HPL Euro oil, as at least they "meet" MB specs.