Aftermarket and OEM Parts: What’s the Difference?

Every time your car needs attention – whether for routine maintenance, repairs from an accident, or anything in between – you, as a consumer, are exercising your choice. Taking it to the dealership’s service department is one choice. You can also take it to an independent shop. For some who are particularly handy and so inclined, you could do the repairs yourself.

While you’re picking where to take your vehicle, you’re also creating opportunities for other choices – between Original Equipment Manufacturer (OEM) parts and those created by alternative parts manufacturers – sometimes called aftermarket parts.

What’s the difference between these two? Does it matter which you use?

What are OEM and Alternative Parts?

Let’s start with understanding the difference between alternative parts and OEM parts.

The commonly accepted definition of an OEM part is one that is made by the vehicle’s manufacturer. These are the parts that were created by the car company and should match what was on your car when it rolled out of the factory.

Alternative parts, on the other hand, are parts made by anyone other than the OEM. You’re probably very familiar with some of the more popular name brands, especially for things like tires, spark plugs, and oil filters. With other alternative replacements, you may not think about the brand, like windshield wipers and headlights. And it may not even occur to you that other alternative parts, such as hoods, bumpers mirrors, and fenders, normally known as collision parts, are available from non-OEM suppliers. There are thousands of alternative parts available, and the alternative parts industry has been around for more than 100 years.

What you may not realize is that some of the parts that are on your car when it comes off the assembly line are, by definition, alternative parts. Sometimes called “genuine parts”, these parts aren’t made by the OEM but are chosen by the car manufacturer to be installed when the car was built and are frequently imprinted with the automobile company’s logo, even though it was not manufactured by them. To simplify this discussion, however, we’ll treat these parts as if we were discussing OEM parts.

The Differences Between Alternative and OEM Parts

The differences between alternative and OEM are startlingly few.


Easy to choose: OEM service parts come with presumed confidence as they are usually the same as the original parts used when the car is assembled. However, they are extremely expensive and occasionally the car company will discontinue the original part and rely on an OE aftermarket part.

Quality is the same as the original:OEM service parts quality will normally be the same as the original parts on your car.

Part warranty: The OEM service parts will come with a limited, 90 day warranty.


Cost: Alternative parts can be as much as 50% less than OEM parts.

Selection: You’ll have a wide selection of parts to choose from.

Availability:Because alternative parts are made by a number of manufacturers, they are more widely available than OEM parts.

Potentially better quality: Many alternative parts are designed to work as well or even better than the OEM part that it replaces.

Protect Your Right to Choose Your Vehicle Replacement Parts

Whichever you decide to go with, make sure you exercise your right as an informed consumer. Shop around, do your research, and understand what effect the parts you choose will have on your car. In many cases, the difference is minimal, other than price. However, having a choice is important to what your car costs to repair today, and what it may cost tomorrow.

Competition and choice are what drives the market and keeps prices reasonable for consumers.

If you’re concerned about the auto manufacturers eliminating the competition and your right to choose what parts are used to repair or maintain your car, contact your state or federal representative and let them know your thoughts. You can also file a complaint with the FTC at their Complaint Assistant website.


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