The technician will put the vehicle in neutral on the lift, rotate the wheels, and listen for any abnormal metal gear whine from inside the motor reducer, and check for gear oil leaks at the joints of the reducer housing.

Test-drive cars experience much more mechanical wear due to extreme conditions like cold starts and emergency braking compared to regular family cars. We can identify this by tracing whether the first owner was a 4S dealership or the manufacturer. If so, we will reassess its value based on "operational intensity" standards.

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).