This article is a summary of the original article published by IBIA
There are many misconceptions about the new VLSFO (Very low sulfur fuel oil) 0.5% sulfur max fuel. We haven't yet seen any quality claim on the VLSFO supply, but since every supplier has their own method of blending or refining, we need to make sure we forward the typical specification to the engineers onboard to ensure clarity and avoid any problems.
“There is no specification for VLSFO”?... This is a misconception!
Since the beginning of 2020, we have had to give the ISO 8217:2017 specs with 0.5% sulphur limits. But as VLSFO specs were not specifically published for this new fuel, this created some confusion.
ISO 8217:2017 specifies limits, and there are differences between minimum and maximum limits. Residual marine fuels range from very high density/high viscosity (maximum category RMK), to low fuel grades that are close to distillates and (minimum category RMA).
Prior to 2020, the supplier sold HSFO 3.50% classified as RMG 380 or RMG 180 or RMD 80.
Today, depending on the supplier, they have their own style of blending, so the viscosity shows very wide ranges (some as low as 20 or as high as 350). Hence, it seems there are no unified specifications for VLSFO, but VLSFOs (just like HSFOs) are blends that must meet ISO 8217 specifications in order to be commercially viable.