our w210 diesel does excellent on delvac 1... our w123 turbodiesel does excellent too! Id use it without worries, it definitely has a lot more soot handling capacity and whatnot than the 0w-40... plus it wont shear down, though it seems that 30wt oils are ok for the new CDI engines.

Use delvac 1/M1 T&SUV and enjoy that car... Might be the next car that I buy (though I actually prefer the w123 MB diesels the best!)

JMH