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).

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.

The technician will check the production date codes and brand logos in the lower left corner of all the car's glass (including the windshield, four doors, and rear window) to see if they match the vehicle's factory date on the nameplate. If any glass is found to have a date later than the vehicle's production date, it will be recorded as evidence of a "previous damage replacement."