Dr Booth was a professor of a university at Pit*****urg, PA. He owned dozen of MB diesel cars and a well respected figure in a MB forum. He was experimenting with his own cars on different oils and advocated syn oil particularly Mobil 1.
After his death two years ago, the forum was dedicated to him by naming to "Marshall Booth Diesel Forum" in Mercedes Benz Club of America:
The Marshall Booth Diesel Forum
Surf it if interested...