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).

4S dealership records are directly connected to the manufacturer's database, making the data hard to tamper with and the most reliable, with original parts guaranteed; third-party repair shops usually are not connected, making their data unverifiable. Therefore, we only consider the connected records from 4S dealerships as valid historical documentation.

Under international practices and our standard CIF/FOB terms, the THC at the port of origin (China) is borne by the seller; all THC and port miscellaneous charges incurred at the destination port during unloading are to be paid by the buyer (consignee) upon local customs clearance and pickup.