California experienced a 300% increase in loss of propulsion (LOP) incidents since its distillate fuel regulation came into effect in 2009. The compression ignition (Diesel) engines aboard modern cargo ships over 10,000 gross tons use 3.0% sulfur Heavy Fuel Oil (HFO). This fuel must be heated to flow through the fuel lines because at normal ambient temperature HFO has the consistency of tar. Distillate fuel in contrast does not require the high temperatures, and the thermodynamics of cooling metal, gaskets and seals resulted in leaks, along with filter clogging from engine buildup scrubbing. In addition, the cost savings of using HFO are significant over the use of distillate fuel which is typically around US$300 more per ton.
An evaluation of four residual fuel-oil additives phase 1 - Nalco Project