PaulC, I started the project because I liked the idea of 40 weight synthetic and Delvac was 50 miles away and I didn't want to pay the dealer price for 0W40.
To be perfectly honest, any of the Mobil 1 synthetic oils will probably work fine if changed at reasonable intervals. When my S320 was new, 5W-30 to 10W40 conventenial oils where acceptable for 7500 mile changes. It seems that MB has since decided 40 weight oils are better for whatever reason. Probably because of warranty issues on the FSS vehicles with extended changes.
1984 300D Euro