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).

Apply for a certificate of origin from the local customs or trade promotion agency, proving that the country of manufacture is China. This is a necessary document for customs clearance in regions like the Middle East and Southeast Asia.

Be sure to verify the draft Bill of Lading as soon as possible after the ship departs. Once the original is issued, changes will incur high amendment fees and may prevent the customer from picking up the goods.