Question 6 DDE01 - Designated Duty Engineer - Unlimited HP

The Correct Answer is B **Explanation for B (Correct Answer):** Option B states: "When the oil level rises to the FULL mark on the dipstick." This is the correct procedure for adding make-up oil to an engine. The space between the ADD mark (or LOW mark) and the FULL mark represents the safe operating range. To ensure the engine has the maximum intended lubrication capacity before operation, make-up oil should be added until the dipstick registers exactly at the FULL mark. This prevents oil starvation while avoiding overfilling. **Explanation of Incorrect Options:** * **A) When the oil level rises to the between the ADD and FULL marks on the dipstick:** While this level is within the safe operating range, it means the engine is still running slightly under the optimal fill level. If significant operation is planned, topping off to the FULL mark is the required preventative maintenance action. Stopping "between" the marks is inefficient and leaves the sump volume reduced. * **C) When the oil level rises to the ADD mark on the dipstick:** The ADD mark (or LOW mark) indicates the minimum safe operating level. If the level is already at or near the ADD mark, adding oil *to* this level achieves nothing, as the oil level will still be considered low. Oil should be added *starting* from this level, and stopped at the FULL mark. * **D) When the oil level rises to a level well above the FULL mark on the dipstick:** Overfilling the crankcase is dangerous and potentially damaging to the engine. Excess oil can be churned by the crankshaft (aeration/foaming), leading to reduced lubrication efficiency, increased oil temperature, and possibly excessive pressure build-up or oil leakage through seals and breathers.