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).

Absolutely not. Any secondary damage caused by overseas non-professional repairs, violent disassembly, or the use of inferior replacement fluids will immediately void any form of "extended parts compensation" we provide.

For dealers who purchase the same brand models in bulk over a long term, we can coordinate senior technicians domestically to offer paid, regular Zoom video technical Q&A to resolve the issues you encounter locally.