How should the octane requirement be interpreted?

• A. Lower octane can be used.
• B. Octane must be at least 91.
• C. Octane must be exactly 91.
• D. Octane is irrelevant.

Answer: (B)

The octane requirement tells you the minimum anti-knock quality the engine needs to run smoothly under operating conditions. You should use fuel with an octane rating that is equal to or higher than the specified value to prevent detonation, protect the engine, and maintain performance. So the correct interpretation is that octane must be at least 91. Using fuel with lower octane can cause knocking and potential damage; using higher octane is acceptable but not required for this engine; octane being irrelevant is incorrect.