Marine Diesel Oil (MDO)

Marine diesel is a heavy gas oil usually used for marine purposes only. Typically used by medium speed and medium/high speed marine diesel engines. Also used in the larger slow speed and medium speed propulsion engine which normally burn residual fuel.

Source: http://www.etc-cte.ec.gc.ca/databases/Oilproperties/pdf/WEB_Marine_Diesel_Fuel_Oil.pdf