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).
Rust is a deal-breaker that photos can hide, so be systematic. High-risk areas to check: 1. Underbody and frame rails—surface rust is normal, but flaking or bubbling paint means advanced corrosion 2. Wheel arches and rocker panels—these trap mud and salt 3. Door bottoms and the trunk floor—water collects here; lift the trunk mat and look for dampness or repair welds 4. Around the windshield and sunroof drains—leaks cause hidden rust in the A-pillars Ask the inspector to do a magnet test: filler-repaired areas won't hold a magnet, indicating past accident repairs. A paint thickness gauge reveals resprayed sections—uniform readings around 80-150 microns are normal; spikes over 300 suggest bodywork. Cars from northern China (salted roads in winter) or coastal cities need extra scrutiny on the underbody. If structural members show corrosion, walk away—repairs rarely restore original strength.
A Chinese history report (查博士, 精真估, or 4S-shop records) usually contains several sections. Here's how to read them. Accident records: entries tagged 重大事故 (major accident) or listings at an insurance payout above 30% of the car's value are serious red flags. Airbag deployment is a deal-breaker for most buyers. Mileage timeline: check that mileage increases logically between service visits. A sudden drop between two dates means odometer tampering—walk away. Ownership count: more than 3 owners in 5 years suggests a problem car. Also check the 使用性质 field: a car registered as 营运 (commercial/taxi use) has a much shorter legal lifespan. Maintenance entries: consistent 4S dealership records are a good sign; long gaps aren't necessarily fatal if the owner used independent shops, but ask for receipts. Cross-check the report against the VIN plate, registration certificate, and physical inspection. If the report shows no accidents but paint thickness readings say otherwise, trust the metal, not the paper.
