We use two steps: 1. Insert a medical-grade endoscope through the spark plug hole to visually inspect cylinder wall scratches and carbon buildup on the piston top; 2. Extract an engine oil sample to check for large metal debris or emulsification (caused by coolant leakage).

We use quantitative standards. Minor scratches less than 3 cm that do not reach the base coat (which can be polished) are considered normal wear; scratches over 3 cm deep to the base coat or dents larger than 2 cm in diameter will be highlighted in the inspection report's "Appearance Defect Distribution Map" with close-up photos.

It usually refers to very small stone chips on the hood from high-speed driving, nail scratches on the inside of door handles, slight curb scratches on the edges of wheels, and minor wear on interior plastic parts. These do not affect the vehicle's functionality or corrosion resistance.