Question 6 QMED03 - Oiler

The Correct Answer is D **Explanation for Option D (Lube Oil System):** Heat exchangers (specifically oil coolers) are fundamentally required in the lube oil system of virtually all internal combustion engines, including small auxiliary diesels. The primary function of the lube oil is not only to lubric lubricate moving parts but also to carry away heat generated by friction and combustion. This oil must be cooled before being recirculated to maintain its optimal viscosity and prevent thermal breakdown. Therefore, a heat exchanger (which typically uses jacket water or raw seawater/freshwater to cool the oil) is a standard and essential component of the lube oil system. **Explanation of Incorrect Options:** * **A) Governing system:** The governing system (which controls engine speed/fuel delivery) primarily consists of mechanical or electronic components (actuators, linkages, sensors). It does not require a large heat exchanger or cooler for its primary function. * **B) Fuel oil system:** While fuel oil may sometimes be heated (especially heavy fuel oil) or occasionally cooled (for very high-speed applications or large engines), a heat exchanger is not a "most commonly found" component in the *system* of a small auxiliary diesel engine. Small auxiliary engines typically run on marine diesel oil (MDO) which does not require extensive pre-treatment or specialized cooling/heating. * **C) Air starting system:** The air starting system consists of compressed air receivers, valves, and a starting motor (or distributor). The temperature of the starting air does not need active regulation via a heat exchanger for the system to function.