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).

If there is a minor leak in the lines due to bumps, it is possible that the cooling may not work upon arrival. This is a normal physical loss. The cost of vacuuming, pressure testing, and recharging refrigerant at a local auto repair shop is low and is the buyer's responsibility.

Obtaining precise internal resistance at different SOC levels requires disassembling the battery pack and connecting it to a professional charge-discharge cabinet for several days of cycling tests. This is beyond the scope of non-destructive used car inspections; we only provide real-time estimated internal resistance data based on OBD port readings.