You are onboard a vessel with a slow-speed crosshead type engine. The fuel just received has a significantly lower sulfur content than the previous bunkers. Which of the following would be a concern due to the reduced sulfur content?

Correct Answer: Option B — Base number of the cylinder oil

Switching to ultra-low sulfur fuel reduces acid formation in marine diesel cylinders, requiring engineers to lower the Base Number (BN) of the cylinder lubricating oil to prevent calcium deposits.