During preflight, if checking more than 15 minutes after shutdown, engine oil level should be between which marks?

• A. MIN and MAX
• B. Bottom of the Sight Glass and MIN
• C. MAX and Bottom
• D. Top and Bottom

Answer: (B)

When the engine has been shut down for more than 15 minutes, oil drains back into the reservoir, so the sight glass reading tends to sit lower than its normal operating range. In this situation the acceptable preflight oil level is the lower portion visible in the sight glass—between the bottom edge of the sight glass and the MIN mark. This range accounts for drainback after a cooldown while still ensuring there is enough oil present to protect the engine on restart.

If the level were higher than the MIN mark, it would indicate more oil than the minimum near the top of the range, which isn’t the expected indication after a prolonged shutdown. If it were below the bottom edge, the level would be dangerously low. The other ranges don’t reflect the drainback condition you’re checking for after a long shutdown, so the correct target is the space between the bottom of the sight glass and the MIN mark.