Marine Diesel Oil
Abbreviation: MDO
A distillate fuel oil with low sulfur content, used in auxiliary engines and during port operations where ECA rules apply.
Quick facts
- Regulation
- MARPOL Annex VI
In practice
Engineers switching from HFO to MDO must manage the transition carefully to avoid thermal shock in fuel pipework and to purge residual viscous fuel from injection equipment. MARPOL requires that the changeover procedure, including time, position, and tank quantities, be entered in the Engine Room Log Book before the vessel enters an ECA. Fuel oil samples taken at bunkering are retained and analysed to verify sulphur content compliance, and the results are available to port state control officers on request.
Regulatory detail & full definition
Marine Diesel Oil is a distillate fuel blended to ISO 8217 grades DMA, DMB, or DMZ, with a maximum sulphur content now limited to 0.10% m/m within Emission Control Areas under MARPOL Annex VI Regulation 14. Its relatively low viscosity — typically under 6 cSt at 40 °C — means it can be used at ambient temperatures without preheating, making it the standard fuel for auxiliary engines and for main-engine operation in port, coastal, and ECA waters.
Engineers switching from HFO to MDO must manage the transition carefully to avoid thermal shock in fuel pipework and to purge residual viscous fuel from injection equipment. MARPOL requires that the changeover procedure, including time, position, and tank quantities, be entered in the Engine Room Log Book before the vessel enters an ECA. Fuel oil samples taken at bunkering are retained and analysed to verify sulphur content compliance, and the results are available to port state control officers on request.
Authoritative source: ISO 8217 ↗
Related
Source: ISO 8217
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