What can be used as a tracing powder when checking for small oil leaks?

• A. Talcum powder
• B. Chalk dust
• C. Cornstarch
• D. Aerosol foot powder

Answer: (D)

This question tests choosing a tracing powder with the right properties to reveal tiny oil leaks. You want something ultra-fine, dry, and able to cling to the thin oil film on engine parts so the leak path becomes visible. Aerosol foot powder sprays as a very light, fine coating that will adhere to even small amounts of oil and contrast well against metal surfaces. The oil escaping through a leak will pick up or move the powder, creating a visible trail that marks the leak source and is easy to inspect and clean up afterward.

Other powders tend to be less effective for this purpose. Talcum powder can clump or not spread as evenly, chalk dust is usually coarser and may leave large, less precise deposits, and cornstarch can behave inconsistently with moisture and oil, reducing visibility. Aerosol foot powder’s fine, uniform coverage makes it the better choice for spotting small leaks.