Which document should you consult to determine when to change engine oil?

• A. The vehicle registration
• B. The maintenance schedule in your owner's manual
• C. Your last oil bottle label
• D. The weather forecast

Answer: (B)

The main thing to understand is that the maintenance schedule in your owner's manual provides the official intervals for changing engine oil. This document is tailored to your specific vehicle and tells you how often you should change oil under normal or severe driving conditions, and it may also specify the required oil type and whether a filter change is included. Modern cars might reference an oil-life monitor, but the manual explains how that system works and what intervals it uses. Other options don’t guide service timing—vehicle registration isn’t related to maintenance, a random oil bottle label isn’t vehicle-specific, and weather forecasts don’t determine when you should service the engine.