🔍 Key Concepts

• Meaning of neutralization number in lubricating oil tests • Relationship between acidic contaminants and the amount of base (KOH) needed to neutralize them • Difference between tests for solids content/ash and tests for acidity/alkalinity

💭 Think About

• Ask yourself: does this measurement directly identify the specific type of acid, or does it only measure how much base is required to neutralize all the acids present? • Consider which choice describes a measurement method (how the test is done) rather than an interpretation of contamination type. • Think about which option is clearly about non‑burnable solids or sulfur compounds—are those actually what a standard lubricating oil neutralization test focuses on?

✅ Before You Answer

• Verify that the correct option mentions potassium hydroxide (KOH), which is standard for neutralization number tests. • Confirm that the definition relates to a quantity per measured oil sample (usually in milligrams of KOH per gram of oil). • Eliminate any option that talks mainly about solids or identifying specific acid types, since neutralization number is a bulk acidity measure, not a detailed analysis.