🔍 Key Concepts

• Diesel engine crankcase oil functions (lubrication, cooling, cleaning, neutralizing acids) • Meaning of Total Base Number (TBN) and Total Acid Number (TAN) in lube oil analysis • Difference between physical properties (like viscosity, particle count) and chemical properties (like acid/base neutralizing ability)

💭 Think About

• Which test specifically measures how much alkaline (basic) additive is left in the oil to react with and neutralize acids? • Which measurements mainly tell you about thickness of the oil or contamination level, rather than chemical neutralizing capacity? • Between something called a “base” number and something called an “acid” number, which one describes the remaining reserve to fight acids rather than how much acid is already present?

✅ Before You Answer

• Identify which option refers to the oil’s reserve alkalinity (ability to neutralize acids). • Separate tests that show contamination or wear (like particles or viscosity change) from those that show chemical condition of the oil. • Ask: does this test indicate how much acid is in the oil, or how much ability the oil has to neutralize acid? Pick the latter.