Oilers/Plant Tenders (HHC) Civil Service Practice Exam

In comparing a four-cycle diesel to a single acting two-cycle diesel, which statement is accurate?

1. The two-cycle engine uses less lubricating oil

2. The two-cycle engine uses more lubricating oil

3. Both engines use the same amount of oil

4. The four-cycle engine is more efficient

The correct answer is: The two-cycle engine uses more lubricating oil

The comparison between a four-cycle diesel engine and a single acting two-cycle diesel engine reveals that the two-cycle engine tends to use more lubricating oil. This is primarily due to the operating principles of the two-cycle engine, which requires lubrication to be mixed with the fuel for adequate operation, leading to an increased consumption of oil. In contrast, the four-cycle diesel engine operates in a way that allows it to separate fuel and oil more efficiently. As a result, the lubrication happens independently of the fuel intake, leading to lower overall consumption of lubricating oil. This distinction in their operational mechanics underscores why the two-cycle engine is typically associated with higher oil usage compared to the four-cycle variant. Thus, acknowledging the functional differences in engine design and operation provides a clear understanding of why the statement regarding the two-cycle engine's oil consumption is accurate.