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).

All our measuring instruments (especially calipers, paint thickness gauges, and refrigerant pressure gauges) are calibrated quarterly according to ISO quality management system requirements to ensure the data we provide you is objective, accurate, and reliable.

It's not mandatory. Four-wheel alignment and dynamic balance are part of routine maintenance. During long-distance towing and sea transport, the suspension may experience slight changes in stress. We recommend that buyers perform a four-wheel alignment locally after picking up the vehicle at the destination port and replacing tires suitable for local road conditions.