What are Aftermarket Parts

Aftermarket parts are components for your vehicle made and sold by a company other than your vehicle's manufacturer. These parts can range from things like windshield wiper blade inserts to critically important engine components. Aftermarket parts are used in vehicle maintenance, in body repairs after an accident, to repair your vehicle in the event of a breakdown, and as a way to improve the look or performance of your vehicle.

When your vehicle breaks down or is involved in an accident, you want the vehicle to be made right again. One concern many vehicle owners have is that the parts used in the repair will be substandard. In this context, aftermarket parts is a term that conveys a suspicion that the part is sub-par. By contrast, many vehicle owners who want to increase the performance or look of their vehicle opt for parts that they feel are clearly superior to the parts originally chosen by the manufacturer. Our point is that the term “aftermarket part” need not always have a negative connotation.

What are aftermarket parts

In a general context, an aftermarket part is one that you don’t purchase directly from your automaker’s authorized dealership or retail network. We wish we could extend the definition to be more all-encompassing, but the fact is, many parts one buys from a dealer that are considered “original equipment manufacturer” parts, a.k.a. “OEM” parts, are clearly labeled as having been made by another company other than your automaker. In other cases, the part is “private labeled,” meaning the automaker’s brand is applied to the part, but that part may also be used by other automakers, or perhaps even sold directly to the consumer by that parts supplier.

The most important aspect of any part is that it meets the demands of its application. The automaker, also called the “OEM,” goes to great lengths to select or design parts it feels meet the required budget (often the very first consideration), desired life expectancy, manufacturability, and aesthetics in some cases. Aftermarket parts are no different in this regard.

The fuzzy area in this conversation comes from the fact that automakers don’t actually make many of the parts you will someday replace. They use suppliers to make everything from belts and hoses, filters of all types, pumps, starters, suspension components, brake components (often stamped with the part maker’s name proudly on the outside of the caliper), infotainment systems, and pretty much everything else. Honda does not have a wheel bearing factory operated by Honda employees using raw materials made in Honda factories. It buys wheel bearings from a bearing manufacturer (usually a company called NTN), who itself uses multiple key suppliers in the creation of that wheel bearing.

Many of the parts that OEMs use are made by suppliers who also sell replacement parts or even upgrades directly to the consumer. In other cases, the aftermarket parts provider is a massive company making parts for thousands of individual applications. The idea that aftermarket parts are made by a shady fly-by-night operation someplace in a part of the world seen as less desirable is no longer valid, if it ever was.

What's the difference between aftermarket and OEM parts

The way that an OEM part is different from an aftermarket part is that the automotive manufacturer played a role in its design and selection, and perhaps its manufacturing. Following this participation, the manufacturer assigned that component a part number of its own and set up a distribution network to sell it or use it in dealer repairs. All of this comes at a very high cost to the consumer.

Aftermarket parts, by contrast, are engineered, tested, and manufactured to serve the same purpose as the original part. They are then marketed by the parts manufacturer, or a retail company. One part sold by an aftermarket supplier, let’s call them Acme, may in fact be made by multiple parts manufacturers to Acme’s specifications. And those specifications are very likely identical in all meaningful ways to the original automaker’s. Part of Acme’s overall business may include making OEM parts that they supply to automakers who call them their own.

Quality control is an important part of any manufacturing process. If there is any evidence that automotive manufacturers have superior quality control by comparison to the parts suppliers who make and market aftermarket parts, it’s hard to understand how that could be true. Let’s remember that OEMs often make mistakes. There were 53 million vehicles recalled in the U.S. in 2019 alone. Almost all of those recalls involved the failure of an OEM part that the automaker designed, specified, and took responsibility for the quality of.

Here is a great example. Toyota, Honda, Mazda, Subaru, and other manufacturers are presently struggling with a recall related to failing fuel pumps in their top-selling models. The reason that there is more than one manufacturer involved here is that these manufacturers didn’t make this critically important component. A huge parts manufacturer named Denso made the part they all shared and all applied their own “OEM” part number to. It gets better. Denso used to be owned by Toyota. Now only 25% of the company is owned by Toyota and Denso supplies components to multiple brands of automobiles. Is Denso in actuality then considered an OEM in their own right? The line is often blurred.

If you need another example of an “OEM” part failing and causing a major market disruption, search for “Takata airbag recall” in your browser. This component manufacturer supplied most major brands with OEM airbag inflators. OEMs don’t actually make that critical safety component. When it all went wrong, the OEMs didn’t call the failed part their airbag inflator. Instead, they pointed the finger at the supplier. It became the “Takata airbag recall.”

The point is, automakers want you to think their parts are superior to aftermarket parts. But when their “own parts” fail, they sometimes point at the supplier and name them as the cause.

Aftermarket Parts Pros and Cons

How do aftermarket parts work

If you have your vehicle serviced at the brand’s authorized dealer, you would assume that only original parts made by your automaker will be used in its maintenance or repair. Of course, this is not true. The single most expensive maintenance item on any vehicle is tires. And no automaker manufacturers tires. They don’t even bother to private label them. There are no “Ford SuperRound” tires or “Volkswagen GreatTread” tires. The OEMs buy the same tires from the same companies you do.

Oil is the lifeblood of the modern gasoline-powered vehicle. When you have the oil changed, the oil the dealer puts in is not made by the automaker, though it may well be available at the parts counter in a bottle labeled with the brand’s name and logo. Thus, the two most common and likely most costly components you will change in your vehicle are aftermarket parts, and are openly sold by your automaker inside their own dealerships.

Should you need a replacement alternator, the one the dealer installed may not be the same part number that the brand originally specified. We recently had an original alternator fail in our Subaru Forester. The folks at the Subaru dealership covered the replacement at no cost. Interestingly, the dealer didn’t use the original OEM alternator because the original OEM part was found to have a lifespan of just a few years and was causing trouble with the engine’s performance before it would ultimately fail. As you can see, original parts are sometimes even substituted by the automakers themselves.

One part you will almost certainly change before your vehicle turns five years of age is the 12-volt battery. This is true even if you own an electric vehicle. In the United States, two companies dominate the 12-volt battery business, Johnson Controls, Inc. and Exide Technologies. If you buy a replacement battery from your car dealership it may well have the name of the car brand on it, but they didn’t make it. It was made in the same factory that built all of the aftermarket batteries you could have bought for less from AAA, a local auto parts store, or have installed by a local mechanic.

Aftermarket parts like an oil filter, alternator, starter, AC compressor, wheel bearing, brake rotor, or other commonly-replaced parts are typically the first choice of independent repair shops. These shops know and trust various aftermarket brands because they use them every day to make affordable repairs on cars owned by lifelong customers. These shops know which brands make a quality part for that specific repair. Most importantly, they know that in many cases, the aftermarket parts perform as well or better than the OEM parts that they could source and this will save money for their customers. No shop wants to use a part that will have a distraught customer come back a week later with a car on a flatbed. Don’t assume aftermarket parts used by your trusted local shop are of low quality.

Most of our overview thus far has centered around late-model vehicles and their parts. It’s important to be mindful of the fact that OEM parts for older cars may no longer be available. In many cases, parts with superior performance made by aftermarket suppliers replaced the original part somewhere along the timeline of that model’s existence.

One thing to keep in mind whenever one is purchasing an aftermarket part to repair a vehicle is that the OEM part failed. Had it not failed, the replacement part would not be needed. If you are a fan of the show Wheeler Dealers you may have noticed that many of the problems with the vehicles the show returns to good condition are often solved by the substitution of an aftermarket part that works better than the OEM part did.

Types of popular aftermarket parts

Aftermarket parts break down into the following categories:

• Maintenance items (oil filters, tires, brake rotors, brake pads, motor oil)
• Replacement mechanical parts (starters, alternators, etc)
• Performance upgrade parts (cold air intakes, louder exhaust, low-mass flywheels, lighting components)
• Interior accessories (floor mats, cargo floor covers, phone holders, seat covers)
• Infotainment and audio upgrades / replacements (radios, speakers)
• Aesthetic replacement parts (wheels, trim pieces like spoilers)
• Collision repair parts (body panels, subframe components, trim, headlights)

Aftermarket parts for collision repair are unusual in that there is an industry group that ranks the quality of the components used by body shops. Called CAPA, the group evaluates components for quality and then applies a special seal to those that meet its quality guidelines for things like fit and finish.

Upgraded aftermarket parts

One important type of aftermarket parts are those that enthusiasts purchase to improve some aspect of their vehicle. Among the most common aftermarket parts of this type are wheels, cold air intakes (a.k.a. engine air filters), exhaust systems, and infotainment/audio systems. Although automakers choose the OEM parts carefully for reliability, affordability, and of course, performance, superior parts are widely available.

When we say superior, we don’t mean in every possible way. The parts are likely to cost more, perhaps be more energy consuming, perhaps less durable in the case of wheels, but they all have an important ability the buyer is looking for. Our next section offers some very common examples.

How do aftermarket parts compare to OEM?

Just like OEM parts, aftermarket parts run the gamut from poor quality to industry-leading high quality. Here is some easy proof that aftermarket suppliers build components that are equal to the quality and performance of automakers’ original parts. Many automakers’ best models have aftermarket parts highlighted as special features.

Let’s take the all-new Ford Mustang Mach-E GT. Ford chose Brembo brakes on the top trim of its most high-tech new performance vehicle. Brembo is both an OEM parts maker and also an aftermarket parts builder and supplier. Another example is the Mazda Miata. This legendary sports car uses a Bilstein shock package on its top trims. Many top truck and SUV models use Rancho suspension parts, and the vehicle manufacturer proudly touts these as upgrades to what they themselves supply on lesser trims. The truth is they usually don’t make those parts either.

A note about regional aftermarket parts stereotypes

For much of the last century, parts made in certain areas of the world were often looked down on as examples of poor quality. This regionality is no longer valid. Vehicle models and components imported from countries around the world, including from places such as China and Turkey, now earn reliability scores equal to or higher than those from the United States, Germany, or Japan.

Ironically, Japan was once the subject of ridicule for its manufacturing quality, but many Japanese brands are widely regarded today as the epitome of a high quality product. Lexus, Toyota, and Mazda products are often ranked first in quality. Looking ahead, most of the global electric vehicle battery capacity for all brands will come from China built from materials sourced from Chinese suppliers.

In 2020, J.D. Power and Associates ranked the factories that earned the highest quality scores around the world. The study looked at which plants built the models with the fewest defects. A plant operated by General Motors/SAIC in a plant in Shandong Province, China scored highest for initial quality. The model built there, the Buick Envision, has been a huge success for GM, and was one of the first Chinese-built automobiles imported for sale in America. In addition to being notable for its build quality, the Chinese-built Envision earned the highest possible safety scores from IIHS.

You may recall our mention above that the collision repair aftermarket industry has a quality organization called CAPA. Scan down CAPA’s list of approved suppliers and you will quickly notice that the majority are Chinese companies. We also highlighted Brembo, the Italian brake company. Where does the Italian brake company of choice for the Corvette and Mustang Mach-E GT manufacture its brake parts? Nanjing China.

Where to purchase aftermarket parts

You can purchase aftermarket parts at an authorized vehicle dealership’s parts counter, at any auto parts chain near your home such as Autozone, NAPA, or O’Reilly. Or Advanced Auto. You can also purchase aftermarket parts online from retailers like Amazon. You can also obtain them as part of a repair for a local chain or repair service providers like Midas, Meineke, Carstar, AAMCO, Precision or others. And of course you can obtain aftermarket parts when you use your local independent repair shop. Aftermarket parts are now the standard in the industry for automotive repair and available anywhere you buy parts or have your vehicle repaired.

If you opt to buy a part online, check out the reviews. See what people are saying about how the part performed. If you are having your vehicle repaired by a local shop, ask about the parts the shop plans to use. An important consideration is warranty. Quality parts typically have a strong warranty, often one year from date of install. Some are warrantied for the life of the vehicle. In some cases, your local shop may offer a choice of parts that have a longer warranty, or lifetime warranty, but at a slightly higher cost than other options.

About the author,John Goreham has a mechanical engineering degree and spent two decades working in the semiconductor, automotive component, and bio-pharma manufacturing industries. His employers included both original equipment manufacturers, and aftermarket parts suppliers. John has been an accredited automotive media member for ten years and part of the Car Talk team for six.