Two important aspects of proper diesel engine lubrication are:

Proper lubrication in diesel engines is crucial for their efficiency and longevity, and focusing on oil delivery quantity and quality captures two essential elements of this process.

Oil delivery quantity refers to the proper amount of oil reaching critical engine components, ensuring that all moving parts receive adequate lubrication to minimize wear and friction. Insufficient oil delivery can lead to excessive heat and potential engine seizures or failures.

Quality of the oil is equally important, as it affects the engine's performance and protection capabilities. High-quality oils contain additives that prevent oxidation, reduce friction, and offer better cleaning properties to help keep engine parts healthy and functional. Additionally, quality oils maintain their viscosity better over a wider temperature range, ensuring effective lubrication even under harsh operating conditions.

While other factors such as temperature regulation, filtration, pressure maintenance, and oil change frequency are important to overall engine health, they don't encompass the core principles of lubrication as directly as quantity and quality. Temperature regulation and filtration primarily serve to support the lubrication process rather than define it, while viscosity rating and pressure maintenance are also vital but are aspects influenced by the oil's delivery and quality. Thus, highlighting oil delivery quantity and quality aptly summarizes the two vital aspects of maintaining effective lubrication in diesel engines.