Question 12 MODE02 - Assistant MODU Engineer

The Correct Answer is B **Explanation of why Option B is correct:** Oil bath air cleaners rely on oil to trap airborne contaminants (like dust, soot, and grinding particles) before the air enters the engine. The manufacturer's recommended service interval (frequency) is based on standard operating conditions. 1. **Exposure to dusty conditions:** When the engine is exposed to unusually dirty or dusty environments (like open hatch operations, engine room renovations, or activities like arc welding which produce smoke and metal particles), the rate at which contaminants load the oil dramatically increases. Since the oil’s capacity to clean the air is finite, high contamination means the oil will saturate and become ineffective sooner. Therefore, in these conditions, the oil must be replaced **more frequently** than the standard schedule dictates to maintain proper engine protection. 2. **Oil condition (unusually dirty or thickened):** If the oil is visually inspected and found to be unusually dirty (heavily loaded with particulates) or has thickened (due to contamination or moisture), this is a direct indicator that the oil has reached or exceeded its useful life and its filtering efficiency is compromised. Allowing the oil to remain in this condition would risk drawing contaminated air into the engine cylinders. Therefore, if the oil is dirty or thickened, it must be replaced **more frequently** (i.e., immediately, regardless of the schedule) to ensure engine longevity. Both conditions necessitate accelerating the maintenance schedule, making Option B the correct choice. **Explanation of why other options are incorrect:** * **A) Incorrect:** This option correctly states to replace the oil *more frequently* under dusty conditions, but incorrectly states to replace the oil *less frequently* when the oil is unusually dirty or thick. Dirty or thick oil is the primary sign that maintenance is urgently needed, requiring immediate replacement (more frequent maintenance). * **C) Incorrect:** This option incorrectly states to replace the oil *less frequently* when exposed to dusty conditions. Dusty conditions accelerate contamination, requiring *more frequent* changes. It correctly identifies that dirty or thick oil requires *more frequent* replacement. * **D) Incorrect:** This option incorrectly states to replace the oil *less frequently* for both conditions. Dusty conditions and visibly dirty/thick oil both indicate an accelerated need for maintenance, requiring the oil to be changed *more frequently* than scheduled.