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 maintain an absolute skeptical attitude. In addition to regular visual inspections, we focus on checking for sediment accumulation around the sunroof drainage channels and look for water stains under the A-pillar trim and front floor mats. This is the only effective physical evidence to determine if the sunroof drainage holes are blocked, leading to hidden leaks.

After receiving the final payment, we will send you the complete set of original customs clearance documents via DHL or FedEx, which typically includes: - Bill of Lading (B/L) - Commercial Invoice - Packing List - Certificate of Origin (CO) - Used Vehicle Export License issued by the Ministry of Commerce of China Note: If your local customs requires additional documents (such as VIN consistency certificate), please inform us in advance before shipping.