Surely a large proportion of those elements would be present in the new oil anyway, esp as it isn't top notch fully synthetic, low ash, etc, that you would put into a modern Benz car.
I suppose it might be your warmer climate, but 15W40 is thicker than recommended in the GB and European markets for an m103 engine. Factory fill was 10W40. Two different dealers filled our m103s with Mobil 1 0W40 for years (sedan filled from 88 k miles) and Shell 5W40 (Wagon filled from 175 k miles). At 208 k miles the wagon is filled with Mobil 1 and doesn't seem to use any between changes, apart from out of that perennial timing cover leak.