You love your classic car. When it needs repair, you want to install the best parts. But what are those? To many enthusiasts, the dogma is: “Buy only original equipment parts at the dealer. Everything else is junk.” Unfortunately, it’s not that simple. The real answer—and everyone will hate this—is “it depends.”
OE VS. OEM Classic Car Parts
First, let’s get the terminology straight. The difference between “original equipment” (OE) and “original equipment manufacturer” (OEM) parts is confusing. OE, or “genuine” parts, are those that should be identical to parts that were installed when the car was built. This should be what you’re getting when you buy parts at the dealership. However, most parts on a car aren’t produced by the car manufacturer; they’re sourced from an outside vendor. OEM refers to that vendor. For example, most electrical parts on GM cars are supplied by AC Delco. So, sure, you can go to the dealership and buy OE plugs, but you can also simply read the part number off your AC Delco plugs and order the exact same OEM part from any number of suppliers for less money. The rub is that many OE parts don’t have the manufacturer’s name on them, so to purchase the equivalent OEM part, you’d need to know who made it.
Although there should be little difference between an OE and OEM part, “little difference” doesn’t mean “no difference.” An OE part might be embossed with the car’s brand, so if a concours judge is checking for such things, there is a difference. Some of what you’re paying for when you buy an OE part at the dealer is peace of mind on the provenance. If you’re buying the part from a trusted high-volume supplier, you should be okay, but an OE or OEM part on eBay in an open box from an individual or low-volume seller could be returned goods. The world is full of counterfeit parts, sometimes with stamped logos and color-printed factory boxes, so if you see an online merchant advertising “genuine” parts that are dramatically cheaper than those of other sellers, buyer beware.
If you own a car for which there is no longer any dealer network, there is no dealer counter from which to buy OE parts and probably scant few OEM parts, so you’re left with decent-quality used parts or…
OEM Replacement Classic Car Parts
OEM parts are made by the vehicle’s manufacturer. These match the parts that came with your vehicle when it rolled off the assembly line. In some ways, OEM replacement parts are the next-best thing to NOS. These are parts that have been licensed by an automaker to be manufactured by a third-party supplier to fit in the vehicle you are restoring, and as such they come with all the usual guarantees and protections that you’d find with a factory part.
OEM parts come with a few caveats. Car companies will often change suppliers for the same part several times of a period of years, which means components can change slightly in terms of shape, size, functionality, quality, and reliability by the time they make it to the modern parts counter. There’s a chance that whatever you order won’t be a perfect fit for your project, and you may need to make modifications to use the part in question.
PROS
Easier to choose your part: If you go to the parts counter at a dealership and ask for any part, you’ll usually get one type. You don’t have to worry about assessing the quality of different brands and prices.
Greater assurance of quality: The OEM part should work exactly as the one you are replacing. It is what the vehicle was manufactured with and provides a peace of mind in its familiarity and performance.
Comes with a warranty: Most automakers back up their OEM parts with a one-year warranty. And if you get your car repaired at the dealer, they’ll usually stand by their labor as well.
CONS
More expensive: OEM parts will usually cost more than an aftermarket part. When it comes to bodywork, OEM parts tend to cost about 60 percent more, according to the Property Casualty Insurers Association of America (PCI).
Quality may not be superior: You paid the extra money for an OEM part, hoping that it was vastly better than an aftermarket part. But that may not always be the case. So, you might be paying extra just for the name.
Aftermarket parts
Aftermarket parts refer to those produced by any manufacturer other than the OEM. Nowadays, these can even include low-volume 3D-printed parts, but that’s a topic for another day.
There are multiple levels of quality here. Aftermarket parts manufacturers love to bandy about the phrases “OE quality” and “OE spec,” but as there’s no compliance mechanism, these terms are meaningless. You need to read the reviews on enthusiast forums to see what people who have used them have to say.
My feeling is you should have few qualms about installing something like an inexpensive aftermarket hood strut, as it’s easily replaced if it fails, but for labor-intensive parts like lower control arms, it’s probably best to stick with OEM.
Sometimes the aftermarket can supply parts that correct deficiencies the car company was not willing to remedy. For example, it’s common for plastic radiators, expansion tanks, and thermostat housings to crack with age and heat cycling. Their aftermarket aluminum counterparts are generally more reliable. Similarly, certain high-flow water pumps with redesigned impellers outperform the stock water pumps. Do your homework, in other words.
Although sheet-metal and many interior parts are usually unique to a particular make and model, mechanical and electrical parts often aren’t. Brakes, oil pumps, fuel pumps, fuel injectors, all manner of switches, and many other items can often be sourced from sibling makes or models. If you can find cross-reference material on a forum, this kind of “lateral supply” can increase the number of avenues for parts, as well as lower their cost.
PROS
Less expensive: Aftermarket parts are usually less expensive than OEM parts; how much you save varies by brand. Shop around to find the best price and to get an idea of how much that part usually costs. If the price of a part seems too good to be true, ask questions about its quality.
Quality can be equal to or greater than OEM: In some cases, you may end up with a better part than you started with
More variety: There are hundreds of companies that make aftermarket parts. Some specialize in specific parts, and other companies, like NAPA, make almost any part you can think of. More variety means greater selection and a wider range of prices.
Better availability: You can walk into any gas station, auto parts store or local mechanic, and they’re bound to have a part that fits your car. This gives you more options on where to take your car for service.
CONS
Quality varies greatly: The saying “you get what you pay for” rings true here. Some aftermarket parts are inferior because of the use of lower-quality materials. Stick with aftermarket brands you’re familiar with or are recommended by a mechanic you trust, even if these parts cost a bit more.
Overwhelming selection: If you’re not familiar with aftermarket brands, the selection could be overwhelming, and there’s some chance you may get a bad quality part. Even a part as simple as a spark plug can be made by dozens of different companies and comes in numerous variations. Consult your mechanic for advice or simply stick with the OEM part when the price difference isn’t significant.
May not have a warranty: To keep costs down, some aftermarket parts are sold without a warranty.
New Old Stock (NOS) Classic Car Parts
The term new old stock (NOS) refers to old, unused, never-installed OE or OEM parts. For many folks, the original part in the dealer box and wrapper is the holy grail, and for things like body panels, trim, engine blocks, and cylinder heads, NOS parts are often the highest-quality parts available. But for suspension or hydraulic parts, you might not want items that have been sitting on a shelf for decades without their rubber O-rings being exercised.
When a car is new, the only available parts are OE or OEM. Since nearly all cars come with at least a three-year/36,000-mile warranty, the car company has incentive to build them using parts that last at least if that window. If a part is shown to fail quickly, the carmaker might supersede it with an updated part. As cars age and their maintenance needs become known, the aftermarket begins supplying parts. For a period, you might have many choices for normal wear-and-tear parts such as brake pads, water pumps, exhaust systems, shocks, and lower control arms, although something like a dashboard or door card will likely remain a dealer-only item.
But as decades pass and fewer of the cars are still on the road, the sources of parts dry up. GM and Ford dealerships are independently owned, and each dealership appears to be free to liquidate parts inventories if it feels they have aged out of profitability, sending NOS parts into the hands of private companies. Sometimes, normal wear-and-tear parts can still be ordered through the dealer, but body panels and trim parts might get listed in the catalog as no longer available (NLA). At some point, even normal wear-and-tear parts might go on what’s sometimes called worldwide cosmic back order. (Okay, I made that one up.)
If there’s enough pent-up demand, a car company that claims to value its heritage might commission a manufacturer to do a run of parts. These contracts are generally awarded to the lowest bidder, with a resultant decrease in quality. That means you have no guarantee the “OE” part you buy at the dealer will be the same, have the same quality, or even look the same as the one that was originally on the car; the degree to which it is “genuine” might be debatable. I’ve had Bosch-branded points and condensers, purchased at the dealership in BMW boxes, fail inside of 100 miles.
The subject of reproduction parts is a fascinating gray area for what’s “genuine.” The company Original Equipment Reproduction, or OER, provides restoration parts for GM and Chrysler Group cars. Its website says: “Many OER products are officially licensed by General Motors and the Chrysler Group. All OER parts are reverse engineered or manufactured using the original blueprints when available to ensure the closest possible reproduction available on the market. When available, original factory tooling is utilized to insure [sic] complete originality.”
NORS
NORS parts are an unusual niche that walks the line between New Old Stock and OEM. ‘New Old Replacement Stock’ can be thought of as period-correct replacement parts and are often branded by their manufacturer instead of the automaker.
Replica/Reproduction/Remanufactured Parts
If NOS parts are a little too expensive and you can’t find the OEM replacements you are looking for, then it’s time to broaden your search to include the wild, wild west of replicas, reproductions, and remanufactured parts.
Replica and reproduction parts are just what they sound like: the efforts of third-party companies to produce components that match the factory, only without all pesky costs associated with licensing. Sometimes called ‘jobber’ parts, due to their popularity with budget body shops and mechanics, they will get the ‘job’ done, but often have trouble matching genuine gear when it comes to fit or quality.
There are also companies out there making high-end reproductions of parts for cars that have almost no support from either the aftermarket or the factory. Navigating the world of replicas means doing your due diligence on who is reputable and who isn’t before making a purchase.
Remanufactured parts will be familiar to almost anyone who’s worked on a project car. These components are refurbished versions of used parts that have been rebuilt to work like new. They come with a guarantee, and almost always require a core exchange where you send the seller the component you are replacing. They can be a very cost-effective way to repair expensive mechanical parts if you’re not concerned with originality.
Used Classic Car Parts
Wait, used parts in a restoration? For some projects, picking up a parts car to pick clean can often be the most cost-effective way to get a vehicle back on the road. Some items, such as trim pieces, fasteners, electrical components, and interior details can be very difficult to source any other way. The same goes for sheet metal, especially if originality is important to you.
The Challenge
At some point, a car company might stop supporting its cars entirely. Many of them have. Enthusiasts can chest-beat about genuine dealer parts all they want, but you can’t buy what’s no longer available.
Well, then, OE, OEM, aftermarket, or NOS? As I said, it depends. So probably all of them, in some appropriate mix.
NOS, OEM, Or Replica Parts?
When restoring a classic car, no matter how old or what type of vehicle it might be, you’re going to have several different options when choosing replacement parts. In fact, it can often be confusing to try to work through all the choices available to you and decide which ones are the best match for the spirit (and budget) of your project.
One thing to keep in mind is that there’s always a chance you’ll be able to order brand new factory parts that still fit your classic, particularly if it shares its lineage with an existing model. For example, when searching for flywheel bolts for my first-generation Datsun I discovered that Nissan has used the same part on every single manual transmission car it has ever built—including the modern Z. One quick trip to the dealership and I had all the bolts I needed.
If you can’t locate what you need from the factory, there are several different tiers when it comes to restoration parts, which come with varying degrees of quality, cost, and availability. Understanding what each type of replacement component has to offer will help you make the right decision when ordering the parts, you need.
