Use credit check apps (like Check Doctor or Ant Queen) to pull the complete accident record.

We will directly check the registration certificate (the big green book) and count the number of changes.

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).