During preflight, which instrument is used to verify the engine oil level?

During preflight, which instrument is used to verify the engine oil level?

• A. Sight Glass
• B. Dipstick
• C. Pressure Gauge
• D. Tachometer

Answer: (A)

A visual sight through the engine oil reservoir’s sight glass gives the oil quantity directly during preflight. This tiny window shows the actual level, usually with upper and lower marks, so you can confirm the oil sits within the acceptable range with the engine off and after the oil has had time to settle. A dipstick would require removing a cap and reading a mark, which isn’t how this system is checked. The other instruments—pressure gauge and tachometer—measure oil pressure and engine RPM, not the amount of oil in the reservoir. If the sight glass indicates low, add the specified oil and recheck to ensure the level remains between the marked limits.

A visual sight through the engine oil reservoir’s sight glass gives the oil quantity directly during preflight. This tiny window shows the actual level, usually with upper and lower marks, so you can confirm the oil sits within the acceptable range with the engine off and after the oil has had time to settle. A dipstick would require removing a cap and reading a mark, which isn’t how this system is checked. The other instruments—pressure gauge and tachometer—measure oil pressure and engine RPM, not the amount of oil in the reservoir. If the sight glass indicates low, add the specified oil and recheck to ensure the level remains between the marked limits.