the MSL must be pretty good otherwise they wouldn't recommend it for the common rail 4D56....I wouldn't put it in the old single cam 4D56, it wouldn't stay in for a start. The Merc has done 300,000km on 10W40, it would love the 5W40....the Volvo T5 has done 200,000km on tar, I'll go for the 5W40 after I've run the Fuchs through it for 5,000km