I have a 1.7cdi(turbodiesel) and 125 horsepover. I am running their 5/30 oil for 18000miles(30000km). It works great. I have been using Castrol syntec, but it only gave me 14000miles. It has a oil-life monitor that meassure the particles in the oil. The Mercedes-people don't understand why this car is going so long on the same oil, because other people with the same car and engine rarely do more than 12000miles. Could of course be because of this additive that I have been using: www.xado-us.com Bought the car new in November the 14, 2003. It now has 77000miles on(125000km). My other car uses the same oil and the same additive. I drive it hard, but the engine seem to be better than new, and does not use oil between changes. It now has 205700miles on, or 331000km.
I've been running the RP15w40 in my duramax for about 60,000 miles and feel it is a very good oil. I know there is alot of postings here that don't like it but all my results have been good and the price is right if you find the right supplier.The last case I picked up was cheaper than Mobil 1 suv.
A friend of mine has run the Royal Purple 15-40 diesel oil in his 6.0 PSD. His OCI is 15,000. He has never done an analysis, but I have nugged him into letting me do one before he dumps the next batch out of his engine.
He tells me that he uses zero makeup oil between Oci's....wow, very good for a diesel or any engine if you ask me. I am trying to talk him into a bypass filter for extending his OCI's, but if the oil shows good @ 15K why bother. The only advantage is if the Ea type bypass removes soot and that would be an advantage for diesel engines.