🔍 Key Concepts

• Purpose of lubricating oil in a diesel engine and how contamination affects bearings, pistons, and clearances • How fuel oil and lube oil differ in viscosity, additives, and function • When contamination is described as “seriously contaminated” – what that implies about the condition and safety of the oil

💭 Think About

• Think about whether you can ever fully trust lube oil again once it has been heavily diluted with fuel, even if some fuel is removed. • Consider what engine manufacturers and class societies generally recommend when critical fluids are badly contaminated: partial treatment or complete renewal? • Ask yourself which method best guarantees correct lubricating properties (viscosity, film strength) are restored quickly and safely for continued operation.

✅ Before You Answer

• Verify which options are treatment methods that try to clean and reuse the existing oil versus removal and replacement. • Consider whether filters, settlers, or centrifuges are designed primarily for normal small contamination or for oil that is already described as “seriously contaminated.” • Check which choice gives the most reliable protection to engine bearings and moving parts after major contamination.