I have a 2006 MBSLK...50k miles. I have been using M1 0w-40 oil for awhile. The dealership is now using 5w-40 ESP oil. And from what I uderstand, the ESP oil is more for deisel engines since it is a "low ash" oil and that it dosn't have as much of the additives that the NON ESP oil has. With that being said, I would like to try a new oil. I was interested in Amsoil, but the oil they reccomend and has the MB 229.3 & 229.51 approval is 0w-40 ESP European Formula. They said that the regular SS 0w-40 is not approved for my car??? Any thoughts from the experts?