Which statement best describes engine oil analysis in EVT maintenance?

• A. It can determine the exact cause of engine failure without further testing.
• B. It cannot reveal wear metals or contaminants.
• C. It can reveal wear metals and contaminants indicating engine wear or coolant/fuel intrusion; may trigger an oil change, further diagnostics, or component replacement.
• D. It is only used to determine oil color.

Answer: (C)

Engine oil analysis serves as a diagnostic screening tool that looks for signs of wear and contamination inside an engine. By examining used oil, technicians can detect wear metals shed from internal components (such as iron, aluminum, copper, chromium, and others) and contaminants that indicate coolant or fuel intrusion. A rising or abnormal level of these metals or contaminants signals engine wear or intrusion and helps guide maintenance decisions—such as performing an oil change, conducting further diagnostics (compression tests, leak-down tests, borescope inspection, or cooling-system checks), or replacing affected components. This method does not pinpoint the exact root cause of a failure on its own; it provides a health snapshot and trend data that, when combined with other tests, leads to informed action. It also isn’t reliable to judge overall condition by oil color alone, which is why the analytical results and trends matter far more.