🔍 Key Concepts

• Detergent-type lube oil purpose in diesel engines (suspending soot/keeping engine clean) • Normal color change of detergent oil during correct use vs. signs of actual contamination or breakdown • Effects of fuel dilution and blue exhaust smoke on lubrication quality and engine condition

💭 Think About

• Which of the listed conditions is part of normal operation for detergent-type oil, and which indicate that the oil properties or engine condition are becoming unsafe? • Does a small percentage of fuel dilution automatically require an oil change, or is there an industry ‘limit’ where lubrication is no longer reliable? • What does blue smoke from the exhaust usually indicate about lube oil consumption or condition in a diesel engine?

✅ Before You Answer

• Clarify what is normal for detergent oil appearance vs. what is abnormal or harmful • Consider typical acceptable percentages of fuel dilution in crankcase oil before service is recommended • Think about whether the question is asking for the first clear sign that the oil should be replaced, or if it implies that multiple listed conditions can all be valid triggers