🔍 Key Concepts

• Manufacturer’s maintenance schedule for diesel engines • Difference between time-based (hours of operation) and condition-based maintenance • Why over-changing or under-changing lube oil can be harmful or wasteful

💭 Think About

• Which option gives flexibility for different engine sizes, loads, and operating conditions? • Would a fixed number of hours or “every trip” make sense for all vessels, from small harbor boats to large ocean-going ships? • How do professional engineers and mechanics usually decide maintenance intervals on modern engines?

✅ Before You Answer

• Check which answer best reflects industry practice and modern engineering (not just a convenient number) • Identify which options are too extreme or unrealistic for real-world operations • Consider which choice would be consistent with the engine’s warranty and safe operation