Motor Plants & Auxiliary Boilers USCG Question #397 (Set 9)

A diesel engine should use which type of lubricating oil?

Official USCG Answer & Rule Citation

Correct Answer: Option D — Detergent oil

Modern diesel engines mandate detergent-dispersant lubricating oils to chemically suspend combustion byproducts, soot, and carbonaceous particles, preventing sludge and varnish accumulation on critical internal moving parts.

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