I've come across the ESP M version for Mercedes vehicles, and was wondering out of curiosity if the base/additive package is the same as the 5W-30 version. The 5W-30 is almost a 5W-40, whilst the 5W-40 is only slightly thicker than the 5W-30. It appears the 5W-30 is French and the 5W-40 is American, with the later being significantly cheaper - $52 for a pack of 6 vs. $105. Could this be because the 5W-40 does not have all the other (BMW, VW, etc.) approvals and hence that's driven down the cost? Or a cheaper base stock perhaps?