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).

Testing is mandatory. Troubleshooting electrical devices in the car is part of the standard procedure. We will test the window lift motors, mirror folding, air conditioning compressor and fan, electric seat tracks, etc. Any stuttering or failure of electronic components will be recorded.

We do not rely on the seller's verbal assurances. We provide multi-dimensional accident-free certification by cross-referencing insurance claims records, service orders from authorized dealerships, and conducting on-site paint thickness measurements and weld point inspections of the chassis and structural components (longitudinal beams, A/B/C pillars, shock absorber mounts).