Buying a used car without a proper inspection is a gamble. A pre-purchase inspection identifies existing problems, upcoming maintenance costs, and potential deal-breakers before you hand over your money. Whether you inspect the vehicle yourself or hire a professional, knowing what to check gives you negotiating power and helps you avoid costly surprises.
External Inspection
Walk around the vehicle and look for paint colour differences between panels (indicating previous repair or respray), uneven panel gaps (suggesting collision damage or poor repair), rust bubbles around wheel arches, door bottoms, and sill panels, and any signs of overspray on rubber seals or trim. Check all glass for chips and cracks. Inspect the tyres for remaining tread depth (the legal minimum in Australia is 1.5 mm, but look for at least 3 mm), uneven wear patterns (which may indicate alignment or suspension issues), and matching brands and sizes across each axle.
Under the Bonnet
With the engine cold, check the oil level and condition on the dipstick. Clean amber oil is good, dark brown is normal for oil that is due for a change, and milky or grey oil suggests coolant contamination from a head gasket failure. Check the coolant level and colour in the expansion tank – it should be the correct colour for the coolant type and should be clear, not brown or oily. Check the brake fluid level and colour. Inspect all belts for cracking and all hoses for swelling, cracking, or leaks. Look for oil seeps around the rocker cover gasket, timing cover, and the bottom of the engine.
Engine Start and Idle
Start the engine from cold (ask the seller not to warm it up before you arrive). A healthy engine should start within a second or two of cranking and idle smoothly without hunting or misfiring. Blue smoke from the exhaust at startup indicates oil burning (worn valve seals or piston rings). White smoke that persists after warming up suggests a head gasket issue. Black smoke indicates a rich fuel mixture. Listen for ticking, knocking, or rattling from the engine. Some lifter tick at cold startup is normal on certain engines, but persistent knocking when warm is a red flag.
Dashboard Check
With the ignition on but the engine not running, verify that all warning lights illuminate briefly. This confirms they have not been disabled to hide faults. The check engine, ABS, airbag, and oil pressure lights should all come on and then turn off once the engine is started. Any light that stays on after starting indicates a fault. Use an OBD-II scanner to check for stored and pending fault codes. See our OBD-II codes guide for help interpreting what you find.
Test Drive
Drive the vehicle at various speeds on different road surfaces. Check that the transmission shifts smoothly through all gears without hesitation, harshness, or slipping. Listen for any unusual noises: humming that changes with speed (wheel bearings), clicking when turning (CV joints), clunking over bumps (suspension), or whining from the engine bay (belt or pump bearings). Test the brakes for smooth stopping without pulling, pulsation, or grinding. Check the steering for play or vibration at highway speed. See our noise diagnosis guide and vibration guide for help identifying what you hear and feel.
Underneath the Vehicle
If possible, get the vehicle on a hoist or at least look underneath with a torch. Check for fluid leaks (oil, coolant, transmission fluid, differential fluid), rust on the chassis and subframe, damaged or sagging exhaust components, torn CV boots with grease splatter, leaking shock absorbers (visible oil on the body), and worn bushings or ball joints with visible cracking or play.
Documentation Check
Verify the VIN on the dashboard matches the registration papers, door jamb sticker, and compliance plate. Mismatched VINs are a red flag for a rebirthed or stolen vehicle. See our VIN guide for more on decoding VINs. Check the service history for regularity and look for evidence that major service items like timing belt, transmission fluid, and coolant flush have been done at the correct intervals. Run a PPSR check to verify the vehicle is not encumbered, stolen, or written off.
Know What You Are Looking At
A vehicle-specific workshop manual tells you the exact service intervals, fluid specifications, and wear limits for the vehicle you are inspecting. It also helps you estimate upcoming maintenance costs by showing what is due at each service interval. If you are buying a vehicle you plan to maintain yourself, having the workshop manual from day one is a worthwhile investment. MechanicMate offers PDF workshop manuals for over 960 vehicle models at mechanicmate.net/shop.
