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).

Because it's not a one-time transaction. Only by ensuring compliance checks, improving after-sales service, and providing parts can a good reputation be established, leading to repeat purchases and long-term cooperation.

Under normal circumstances, it takes 15 to 25 working days. This includes: domestic transfer of ownership (3-5 days), applying for an export license (3-5 days), inland trucking to the port (2-5 days), customs inspection and waiting for loading schedule (5-10 days). Do not trust false promises from other channels claiming 'loading within a week.'