The unit of viscosity used is the Centistoke and the fuels most frequently quoted are listed below in order of cost, the least expensive first-* IFO 380 - Intermediate fuel oil with a maximum viscosity of 380 Centistokes (<3.5% sulphur)* IFO 180 - Intermediate fuel oil with a maximum viscosity of 180 Centistokes (<3.5% sulphur)* LS 380 - Low-sulphur (<1.0%) intermediate fuel oil with a maximum viscosity of 380 Centistokes* LS 180 - Low-sulphur (<1.0%) intermediate fuel oil with a maximum viscosity of 180 Centistokes* MDO - Marine diesel oil.
Kljub temu goriva še vedno kotirajo na mednarodnih trgih bunkerejev s svojo najvišjo viskoznostjo (ki pa jo nastavi ISO 8217 standard - glej spodaj), zaradi dejstva, da so morski motorji so zasnovani za uporabo različnih viskoznosti goriva enoto.