Dirty. This expression is regulary used in tanker freight market reports and refers to fixtures for “dirty” oils, e.g., fuel oil, lubricating oil and crude oil, in contrast with “clean oils”, e.g., gasoline, diesel oil, etc. A “dirty service” is the tanker transportation of crude oil and residual fuels. A “dirty ship” is a tanker which has been carrying crude and heavy persistent oils such as fuel oil. “Dirty ballast” is ballast that is carried in unwashed cargo oil tanks.