Strict definition: All metal body parts (doors, hood, fenders) and the frame must retain the original factory paint, with uniform paint thickness readings. Minor touch-ups or replacements of plastic bumpers, as they do not affect metal corrosion protection and vehicle structure, can still be classified as "original paint" in a broad sense, but we will separately note the condition of the bumper.

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).

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.