Question 14 OSE02 - Assistant Engineer - OSV

The Correct Answer is C **Why Option C is Correct:** Option C states that the oil level should be between the FULL and ADD (or LOW) marks on the dipstick when the engine is off (off-line). This is the standard operational range for engine lubrication systems. * **FULL Mark (Maximum Safe Level):** Indicates the highest safe level of oil required for proper lubrication and cooling. Exceeding this can lead to issues like foaming (aeration) of the oil due to the crankshaft splashing it, increased internal pressure, and potential damage to seals. * **ADD/LOW Mark (Minimum Safe Level):** Indicates the minimum level necessary to maintain adequate oil pressure and circulation. Dropping below this level risks oil starvation, overheating, and severe engine damage, especially during startup or when the vessel is maneuvering. * **Ideal Operational Range:** Keeping the oil level within this defined range ensures the engine has sufficient lubrication capacity without being overfilled, optimizing performance and longevity. **Why the Other Options are Incorrect:** * **A) The level should be below the ADD mark on the dipstick.** This is incorrect. A level below the ADD mark indicates the oil is critically low. Operating or starting the engine at this level risks oil starvation, loss of oil pressure, and catastrophic engine failure. The oil should be topped up immediately. * **B) The level should be well above the FULL mark on the dipstick.** This is incorrect. Overfilling the crankcase is detrimental. Excessive oil can be churned and whipped into foam by the moving crankshaft and connecting rods (aeration). Foaming reduces the oil's lubricating properties and volumetric efficiency, leading to inadequate bearing protection, increased oil consumption (due to being forced past seals and breathers), and potential damage. * **D) The actual level is unimportant as long as it is visible on the dipstick.** This is incorrect. The actual level is crucial. Visibility on the dipstick only confirms the presence of oil, not the adequate quantity required for safe operation. The ADD and FULL marks exist precisely because the quantity (level) determines the health and safety margin of the engine's lubrication system.