I don't know if it makes sense or not, but per "FACTORY APPROVED SERVICE PRODUCTS", Section B for S3 engines, synth oils are not listed.
New AMG Benzs come with Mobile 1 all others in my part of the USA have 20-50w oil.
You have opened a can of worms and just wait for all of the suportive and negative data that will follow.
Happy Trails Beep Beep from Houston!!!
Don, El Cheapo