My personal opinion is that I would first buy sockets from Mercedes. See if they fit and if they do, throw those in the garbage. If the the injection pump fuel rod socket were to pop off during driving, the engine would run severely lean momentarily and possibly cause damage to the engine. Not worth the risk. The sockets are not that expensive. FYI, the Mercedes sockets that have LH threads are marked for easy identification.
The only reason I mentioned the grease in the socket, is that it is commonly understood that it is good to use in unsealed sockets. It is not for the reason I listed and and hopefully prevent someone else from doing that.