We use an internationally certified electronic signature platform (such as DocuSign or Adobe Sign). Each signed contract generates a digital certificate with a timestamp and encrypted hash value, which has full legal defense effectiveness in international arbitration courts.

International wire transfers generally follow "shared (SHA)" or "sender pays all (OUR)" principles. To ensure we receive the full remaining payment to release the bill of lading, we require all buyers to choose the "OUR" option when remitting, covering all intermediary bank fees.

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).