Engineering · Lubrication — Viscosity
The viscosity index of a lubricating oil describes:
- AIts flash point
- BIts sulfur content
- CHow little its viscosity changes with temperature (higher VI = more stable)✓ Correct
- DIts pour point only
Explanation
A high viscosity index oil thins less as it heats and thickens less as it cools, maintaining a more constant film. Multigrade oils achieve a high VI with additives so they lubricate over a wide temperature range.
Authority: Modern Marine Engineer's Manual; lubricants
Practice the full Engineering bank
Free spaced-repetition quizzing across 2190 USCG exam questions — it schedules your reviews so the ones you miss come back until they stick.
Related Engineering questions
- Diesel — Operating Cycle
In a four-stroke-cycle diesel engine, the events occur in which order?
- Diesel — Operating Cycle
Compared with a four-stroke engine of the same speed and cylinder size, a two-stroke-cycle diesel produces a power stroke:
- Diesel — Air Systems
The primary purpose of scavenging in a two-stroke diesel engine is to:
- Diesel — Air Systems
A turbocharger increases engine power output mainly by:
- Diesel — Combustion
Ignition of the fuel in a diesel engine is initiated by:
- Diesel — Fuel
The cetane number of a diesel fuel is a measure of its: