Question 7 OSE02 - Assistant Engineer - OSV

The Correct Answer is C. **Why Option C is Correct:** The primary purpose of adding make-up oil to a running or standing engine is to ensure the lubricating oil quantity is sufficient for safe operation, preventing pump cavitation and starvation. The dipstick markings are specifically designed to indicate the safe operating range. When the engine is stopped and the oil is cold (meaning all oil has drained back to the sump and the volume is at its maximum measured state), the maximum safe operating level is indicated by the **FULL** mark. Filling the oil precisely to the FULL mark ensures the engine has the correct, specified volume of lubrication oil, maximizing the time until the next refill is needed while preventing overfilling. **Why Other Options Are Incorrect:** * **A) When the oil level rises to the between the ADD and FULL marks on the side of the dipstick marked ENGINE STOPPED and OIL COLD.** This level indicates the oil quantity is within the acceptable range but is not the target level when conducting a make-up transfer. If you stop adding oil between ADD and FULL, you are intentionally starting the engine with less than the maximum recommended safe volume, which is inefficient management. The goal of adding make-up oil is to restore the level to FULL. * **B) When the oil level rises to a level well above the FULL mark on the side of the dipstick marked ENGINE STOPPED and OIL COLD.** (Note: Option D in the provided list is a duplicate and/or formatting error based on the text, but refers to the same principle). Overfilling the sump (adding oil above the FULL mark) is dangerous. Excess oil can be churned by the crankshaft or connecting rods, leading to aeration (foaming), which degrades the lubricant's performance, reduces oil pressure, and causes premature oxidation. Excessive splash can also cause oil to enter the combustion spaces via piston rings, leading to deposits, fouling, and potential run-away scenarios in certain engine types. * **D) B. When the oil level rises to a level well above the FULL mark... C. When the oil level rises to the FULL mark... D. When the oil level rises to the ADD mark...** (Addressing the structure of the expanded incorrect options): * Adding oil to the ADD mark (the minimum safe level) is incorrect because it means you have not successfully restored the system to the optimal operating volume. * Adding oil well above the FULL mark is incorrect due to the dangers of overfilling (as explained above).