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).

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.

Our bulk discounts are not simply calculated by the number of units, but by shipping batches. Typically, consolidating enough for a 40-foot container (which can hold 2-3 vehicles, depending on size) can waive some logistics fees; purchasing more than 5 units at once triggers tiered discounts.