Why guessing?
These engines were designed primarily for very large container ships.
Older power plants that use oil use crude oil, burn it in order to generate steam from water which than rotates the turbines that rotate generators. Most of the older big ships that used oil also burned crude oil to generate steam that was powering steam engine rotating the propellers. Smaller ships usually use diesel engines.
BTW, this is totally crazy... I mean you can have mechanics go into the engine, check the inlets, outlets, combustion chamber... polish it a bit
Something like – “....hey guys, let's meet at sump for the lunch break” or “...if my wife calls tell her that I’m stuck in 4th cylinder”…