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.

It will cause serious obstacles. China's foreign exchange controls are extremely strict. If the remittance note and the remitter do not match our declared contract, the bank will reject the transaction (Pending). We will need to spend several days submitting additional explanations to the foreign exchange authority, which will inevitably delay the shipping schedule.