With auto repair costs rising, many automobile owners are turning to used auto parts to try to save money. While most auto parts can be safely replaced with used or reconditioned components, there are rules you should always follow. Your safety and that of your riders is the most important factor when considering whether to buy used parts.

DO Have All Your Car's Information

Before you shop for replacement parts, write down your car's VIN number, make, model and year. If the model has more than one engine or transmission size, have those specs too. If you don't have your car's manual, you can find the information online.

DO Buy Used Outer Body Parts

Used body parts are a safe bet most of the time, but you need to do a thorough inspection first. To ensure the part fits properly, make sure it is an original equipment manufacturer (OEM) part. Look for any signs of over-painting, which is almost a certain clue the part has been previously repaired. Knock on the part to see if it has bonding material, which will make a dull thud rather than the ping of metal. Look for signs of rust or rust repair such as cut-away and welded sections. On enclosed parts such as doors, remove the inner panel to check for hidden damage inside.

DO Buy Used Suspension Parts

With one caution to check for worn bushings, used rigid suspension parts are a good buy. The exception to this rule is if the suspension has been damaged in an accident. Minor cracks can turn into huge safety issues quickly at highway speeds, so never buy a damaged suspension, no matter how cheap.

DON'T Buy Used Safety Parts

Anything that has to do with the safety of your car or its passengers should always be purchased new. These include

• electronic system problem sensors
• seat belts
• brake parts
• air bags

DON'T Buy Used Rubber Parts

Rubber is prone to dry rot, and it's difficult to tell how old a part is or how quickly it will fall apart. Hoses and belts are too important to take a chance on. Even used tires can be dangerous, so it's best to buy rubber parts new.

USE CAUTION With Used or Reconditioned Electrical Parts

Unless you are buying from a trusted source, avoid used or remanufactured electrical parts such as starters and alternators. Many times, only the one failed piece of these items is replaced, and the rest of it may be old, worn and ready to fail. Since there is no way to know how many original miles are on the part, it's best to only purchase these from a trusted source, not a discount or budget auto parts shop.

When buying used auto parts, do your homework to ensure you get quality, low mileage parts. Talk to your mechanic or trusted auto parts dealer about which parts are safe to replace with used parts and which you should buy new. Your safety always outweighs the extra cost of new parts.