Despite this, marine fuels are still quoted on the international bunker markets with their maximum viscosity (which is set by the ISO 8217 standard - see below) due to the fact that marine engines are designed to use different viscosities of fuel.
=== Standard in klasifikacija ===CCAI in CII sta dva indeksa, ki opisujeta vžiga kakovosti ostanka kurilnega olja, in CCAI je še posebej pogosto izračunan pri za gorivih za plovila.