Enter a grade (RMG 380, RMK 700, DMA, ISO 8217 DMB) or a trade name (MGO, MDO, IFO 380, HFO 380, VLSFO, ULSFO). Below, an offered grade can be checked against the one wanted.
On the grade alone: the measured values of the fuel are checked on the bunker delivery note and the certificate of quality.
A bunker delivery note says RMG 380 or DMA; the ship’s papers say MGO, IFO 380 or VLSFO. ISO 8217 grades are distillate or residual, and the number of a residual grade is its maximum kinematic viscosity at 50 °C in mm²/s. Enter a grade or a trade name and the reader decodes the designation letter by letter, draws the maximum viscosity among the residual grades on a logarithmic scale, names the editions that list the grade and the sulphur limits, checks an offered grade and writes an RFQ line for fuel-system parts.
Trade names are not ISO grades: an ISO grade is given for a name only where two sources agree. No other limit of the ISO 8217 tables, such as density or flash point, is given here: they changed between editions, and the bunker delivery note and the fuel’s certificate of quality govern. An oil viscosity grade such as ISO VG 68 is covered by the oil viscosity grade converter, a DIN 51502 lubricant code by the lubricant code reader.
D is for distillate fuel, M for marine. In the 2010 and 2017 editions the grades are DMX, DMA, DMZ and DMB; one of the four categories is for diesel engines for emergency purposes. DFA, DFZ and DFB, added in 2017, are DMA, DMZ and DMB with FAME (biodiesel) permitted.
R is for residual fuel. There are six categories, RMA, RMB, RMD, RME, RMG and RMK, and the number after the letters is the maximum kinematic viscosity at 50 °C in mm²/s. RMG and RMK both come with maxima of 380, 500 and 700 and differ in the other limits of the table.
MGO, MDO, IFO, HFO, VLSFO and ULSFO are not ISO grades. VLSFO and ULSFO state only the sulphur content: at most 0.50 % m/m outside emission control areas and at most 0.10 % m/m inside emission control areas (ECA) under MARPOL Annex VI. ISO 8217 sets no sulphur maximum for residual grades: the purchaser states it.
| Grade | Maximum viscosity at 50 °C, mm²/s | ISO 8217:2005 | ISO 8217:2010 | ISO 8217:2017 |
|---|---|---|---|---|
| RMA 10 | 10 | — | listed | listed |
| RMB 30 | 30 | listed | listed | listed |
| RMD 80 | 80 | listed | listed | listed |
| RME 180 | 180 | listed | listed | listed |
| RMG 180 | 180 | — | listed | listed |
| RMG 380 | 380 | listed | listed | listed |
| RMG 500 | 500 | — | listed | listed |
| RMG 700 | 700 | — | listed | listed |
| RMK 380 | 380 | listed | listed | listed |
| RMK 500 | 500 | — | listed | listed |
| RMK 700 | 700 | listed | listed | listed |
| Grade | ISO 8217:2005 | ISO 8217:2010 | ISO 8217:2017 | Note |
|---|---|---|---|---|
| DMX | listed | listed | listed | for diesel engines for emergency purposes |
| DMA | listed | listed | listed | nearest grade to MGO |
| DMZ | — | listed | listed | as DMA, with a higher minimum viscosity at 40 °C |
| DMB | listed | listed | listed | nearest grade to MDO |
| DFA | — | — | listed | as the DM grade with the same letter, with FAME permitted: up to 7.0 % by volume in the 2017 edition, up to 100 % in the 2024 edition |
| DFZ | — | — | listed | as the DM grade with the same letter, with FAME permitted: up to 7.0 % by volume in the 2017 edition, up to 100 % in the 2024 edition |
| DFB | — | — | listed | as the DM grade with the same letter, with FAME permitted: up to 7.0 % by volume in the 2017 edition, up to 100 % in the 2024 edition |
| Name | What it means | ISO grade |
|---|---|---|
| MGO | Marine gas oil, a distillate fuel | nearest: DMA |
| MDO | Marine diesel oil, a distillate fuel | nearest: DMB |
| IFO | Intermediate fuel oil, a residual fuel; the number is the maximum viscosity at 50 °C | the grades with that maximum: for IFO 380, RMG 380 or RMK 380 |
| HFO | Heavy fuel oil, a residual fuel | by the number: for HFO 380, RMG 380 or RMK 380 |
| VLSFO | Sulphur at most 0.50 % m/m | none given |
| ULSFO | Sulphur at most 0.10 % m/m | none given |
The residual maxima are those of the 2010 and 2017 tables, each figure in at least two independent sources; the grade lists of the 2005, 2010 and 2017 editions are each in two or more sources. Left out, because the sources disagree or are too few: every other limit of the tables (density, flash point, CCAI, the distillate sulphur maxima and viscosity at 40 °C, for which the sources give different minima for DMZ); a single grade for IFO 380 and HFO 380 (RMG 380 and RMK 380 share the 380 mm²/s maximum); MGO as DMZ; the grade list of ISO 8217:2024 by name and which high-sulphur residual grades it dropped; whether fuel sold as ULSFO or VLSFO is residual or distillate.
Designations from a summary of ISO 8216-1 and ISO 8217 on a transport policy site and a terminology note of the international bunker industry association; grade tables from the ISO 8217 tables of the 2005, 2010 and 2017 editions as published by three fuel suppliers, a bunker broker and a shipping agent; edition changes from a class society’s 2010 review, the standard’s abstract, a fuel testing laboratory, two notes of the bunker association, a trade journal and two P&I clubs; sulphur limits from the IMO, an encyclopedia and the bunker association; trade names from the data sheets of two suppliers and two refiners and a lubricant maker’s glossary. Every figure and mapping on this page is in at least two of them.
It is the maximum kinematic viscosity of the fuel at 50 °C in mm²/s (cSt): an RMG 380 fuel may be at most 380 mm²/s at 50 °C. Only residual grades carry a number. In the 2010 and 2017 editions of ISO 8217 they are RMA 10, RMB 30, RMD 80, RME 180, RMG 180, 380, 500 and 700, and RMK 380, 500 and 700.
The first letter is the family, D for distillate and R for residual fuel; the second, M, stands for marine. The third letter is the category within the family, and ISO 8217 gives each category its own column of limits. The DF grades, added in 2017, are the distillates in which FAME (biodiesel) is permitted.
IFO 380 is a trade name: an intermediate fuel oil named by its maximum viscosity, 380 mm²/s at 50 °C. Two ISO 8217 grades share that maximum, RMG 380 and RMK 380, and too few of the sources checked pair the name with one of them, so the reader gives both. The bunker delivery note states the grade the fuel was delivered to.
Names for the sulphur content, not ISO grades. VLSFO is fuel oil with at most 0.50 % m/m sulphur, the MARPOL Annex VI limit outside emission control areas since 1 January 2020; ULSFO has at most 0.10 % m/m, the limit inside emission control areas (ECA) since 1 January 2015. ISO 8217 sets no sulphur maximum for residual grades: the purchaser states it.
Vessel Core supplies parts, not fuel. The grade sets what the parts of the fuel system must handle: the purifier, the heaters, the fuel pumps, the injectors and the filters. A request for those parts that gives the grade, the equipment maker and type and the part numbers can be checked before an offer goes back.
The fuel grade shows what the fuel system has to handle; the part is set by the maker, the type and the part number. Add a photograph of the purifier, pump or heater nameplate and the parts list page, and Vessel Core checks them before an offer goes back.
