🔍 Key Concepts

• Lubricating oil properties commonly used in machinery selection • The difference between safety-related properties (like fire/flash point) and performance-related properties • How oils are labeled on containers or in technical manuals (e.g., SAE 30, ISO 68)

💭 Think About

• Which of the choices is most directly related to how thick or thin the oil is during actual use in machinery? • Which properties are mainly used for safety/fire hazard assessment rather than everyday service classification? • When engineers or mechanics say an oil is "30-weight" or "ISO 68," which of these properties are they really talking about?

✅ Before You Answer

• Identify which option is the primary performance characteristic for matching oil to engine/bearing clearances • Separate fire safety properties (those involving ignition or burning) from normal grading properties • Think about what appears in manufacturer specs and oil grades on machinery nameplates and lube charts