Maritime
In the maritime field another type of classification is used for fuel oils:
- MGO (Marine gas oil) - roughly equivalent to No. 2 fuel oil, made from distillate only
- MDO (Marine diesel oil) - A blend of heavy gasoil that may contain very small amounts of black refinery feed stocks, but has a low viscosity up to 12 cSt so it need not be heated for use in internal combustion engines
- IFO (Intermediate fuel oil) A blend of gasoil and heavy fuel oil, with less gasoil than marine diesel oil
- MFO (Marine fuel oil) - same as HFO (just another "naming")
- HFO (Heavy fuel oil) - Pure or nearly pure residual oil, roughly equivalent to No. 6 fuel oil
Marine diesel oil contains some heavy fuel oil, unlike regular diesels. Also, marine fuel oils sometimes contain waste products such as used motor oil.
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