A car has several parts category. In each category there might some that could be interchangeable when buying used auto parts. The best way to buy a used auto part is to disassemble and bring the part, or parts, you need. Or, if the part can easily be compared with it installed on the car, by all means use your car to the place where you are buying the used part. The categories of auto parts are: 1. Engine including electrical or electronic, rubber and plastic parts attached to it. 2. Suspension and under-chassis mechanical parts including bushings. 3. Body parts including windshields, rubber, windows, polyurethane parts, lights, moldings, window risers and door latches and hinges. 4. Electrical wiring, connectors, switches, bulbs and accessories. A good used parts dealer or junkyard should easily be able to identify the part and get you the part, or direct you to the same model if you have to get it yourself. The important thing is for you to know the defect of the part you need. This way, when you see the used part, you know what to check on it. Many mechanical moving parts have some acceptable tolerances of movement. For example, a ball joint should move freely without any feel of ‘grinding within’ and need some effort to move around its socket. As for roller or ball bearings, constant velocity or cross joints, it is advised that you buy brand new. It will require cleaning and close inspection should you want to buy used ones. Junkyards could have some relatively new autos, a year old or less with low mileage that is considered total wreck or loss by insurance companies. Parts of these autos not affected by an accident or prolonged immersion in water should be good. A careful visual inspection of the parts will not be much trouble. Wiring harness still intact within its harness’ corrugated plastic cover should be excellent! Damaged wiring connectors or plugs can easily be changed or by splicing new connectors to the wires. Used electrical devices will be difficult to determine its remaining service life. Do not gamble on them no matter how cheap. Body parts will depend to what extent you would want the parts’ condition. Polyurethane bumpers and parts slightly distorted but not torn or excessively twisted will be easy form back to original. Most will go back to original shape with light taps from a rubber mallet, or immersing them in hot water until they snap back to original shape. Door and rear hood key locks should not be bought as used parts. Even if the dealer has the keys to them you will never know if it has been duplicated by the previous owner/s. Better safe than sorry as they say. For under body and under-chassis parts like springs and shock absorbers, many are interchangeable or fit for different kinds of models or brands. If the dealer or junkyard has testers for these parts and a chart to show limits or tolerances, ask for them to be tested before paying for them. Tires and rims would be better bought as brand new. There is no point taking the risk of running on them. They are the ‘seat’ of road worthiness and safety. Buy used auto parts not out of being a ‘cheapskate’ but for the reason that you know how to buy them. Category:Home › Autos • Will the trend toward economy-size car models lead Americans back to buying smaller-sized cars? — part 2 • You should never use after-market auto parts when maintaining or fixing your car • Should a new car be rust-proofed? • Will the trend toward economy-size car models lead Americans back to buying smaller-sized cars? — part 1 • Five safest cars in North America • How to ensure your teen drives safely after getting a license • Pros and cons of using an hydrogen generator for your car • DIY automotive maintenance: How to change the oil