Thanks all for your responses. It was confusing because MBZ has a list of recommended fluids. According to Amzoil, who I called, the specification is the Dextron III specification and they say that is the critical thing that the fluid meet.. It is recommended on their website which I think gives them legal liability. Something they don't do with the Amzoil that I have been using for the engine: Synthetic Heavy-Duty Diesel & Marine Motor Oil SAE 15W-40 (AME). They do recommend a 5W-30 European Oil so apparently it meets some European spec. He was saying that was possibly meeting an emissions criteria so I'm not going to worry about it. Again, thanks all.