🔍 Key Concepts

• Operational properties of lube oil that affect day‑to‑day engine performance and wear • Difference between lab/analytical properties (used mainly for specification and purchasing) vs. properties you monitor regularly while running machinery • Why viscosity, acidity, and water-separation behavior (demulsibility) matter to bearings, pumps, and clearances

💭 Think About

• When you are standing watch as an engineer, which lube oil properties will you actually trend, test, and adjust for safe operation? • Which group of properties most directly affects oil flow through bearings, corrosion risk to metal surfaces, and the ability to separate water from oil in a crankcase or sump? • Which properties are more about safety limits or fuel/combustion behavior, and which are specifically about lubrication performance inside the machinery?

✅ Before You Answer

• Identify which choice contains properties that you would routinely monitor and send for analysis during normal engine operation • Ask yourself which properties, if out of range, would immediately threaten bearing lubrication, pumpability, or corrosion protection • Separate properties tied mainly to combustion and fuel behavior from those tied to lubrication quality and service life