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).

The registration certificate will show whether the previous owner was an individual (registered with ID) or a company (registered with a business license). Vehicles under a company may be driven by multiple people, so we will focus on checking the uniformity of interior wear and the condition of the chassis.

Based on practical risk assessment, we strongly recommend setting aside 3% to 5% of the car price as a buffer fund for even the highest-rated used cars, to cover oil changes, new tires, minor shipping scratches, and local inspection labor costs.