Both crosshead type and trunk type lubricating oil are received on board a vessel. These two oils cannot be interchanged due to which of the following reasons?

Correct Answer: Option B — Crosshead type lubricating oil has a lower base number as it does not need to neutralize the combustion byproducts

Crosshead (slow-speed) diesel engines utilize separate cylinder and crankcase lubrication systems, requiring a high Base Number (TBN) cylinder oil to neutralize sulfur acids, whereas trunk-piston engines use a single oil serving both functions. Interchanging them fails to provide the required alkalinity and detergency for the specific engine design.