OEM Vs. Aftermarket Spark Plugs: Which Ones Should You Buy?

If you have a bad spark plug in your engine, you’re faced with that age-old question: should you order an OEM spark plug or an aftermarket one?

Sometimes it’s hard to decide between the two types of spark plugs. There are a few key differences between these parts, which we will cover below.

When you’re looking at a few other types of car parts, it may be a toss-up between OEM and aftermarket parts. When it comes to spark plugs, one option is far superior to the other: OEM spark plugs. After reading the following reasons, it will become clear to you why OEM spark plugs are a better investment.

1. OEM Spark Plugs are More Durable Than Aftermarket Spark Plugs

You never have to worry about your OEM spark plugs fizzling out early. The high quality materials and top workmanship guarantee structural integrity and longevity.

Aftermarket spark plugs are usually cheaper than OEM plugs. Aftermarket manufacturers cut corners with inferior quality housings, electrodes, and other components. They take advantage of the fact that it’s pretty difficult to determine the difference between a high-quality spark plug and a low-quality spark plug. It pretty much takes an expert to appraise a new spark plug.

Because OEM spark plugs are built with better quality materials, they last much longer than aftermarket spark plugs do.

2. OEM Spark Plugs Won’t Interfere With Your Car’s Electrical System

You’d find interference resistance pretty high on a list of spark plug design priorities. It’s because spark plugs create so much electrical noise as they fire that it interferes with the rest of the vehicle’s electrical system. That’s why OEM spark plugs are designed with interference suppression resistors. They wall off the electrical noise from the rest of the electrical system.

Many aftermarket spark plugs aren’t built with an interference suppression resistor. If you happen to find an aftermarket spark plug with a resistor built in, chances are high it’s a substandard resistor that won’t do much.

In a nutshell, expect a variety of electrical system issues with a set of aftermarket spark plugs in your engine. Such issues include: radio static, malfunctioning engine sensors, inaccurate ABS sensors, and navigation system issues.

3. OEM Spark Plugs are the Perfect Size and it Matters

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Aftermarket spark plugs have a harder time producing a good amount of spark. It’s because they’re not designed to OE specifications.

Spark plugs have to be just the right size to function well. If you want to get maximum performance and the most mileage out of your vehicle, you have to get spark plugs that aren’t too long or too short. And, they must have just the right electrode design and shape.

Many aftermarket spark plugs come with a one-size-fits-all design. An aftermarket spark plug could work just OK in one vehicle and cause a great loss of horsepower and fuel economy in the next vehicle.

GMC conducted extensive research and testing to figure out the most effective size and design for their spark plugs. They also tweaked the size and design of each variation of their spark plugs to work optimally with the model(s) they’re designed for.

With aftermarket spark plugs, you have to take design into consideration while shopping for a set. Not with OEM spark plugs! Just find the right part number (by looking up your GMC model in our catalog of genuine OEM spark plugs) and you’re good to go.

4. OEM Spark Plugs Cost Less Than Aftermarket Spark Plugs

A lot of people are tempted to buy aftermarket spark plugs because they’re cheap upfront. Still, you know what costs even less? Yep, you guessed it. OEM spark plugs.

Sometimes an OEM spark plug will cost a bit more than an aftermarket spark plug at checkout, but it will save you quite a bit of money in the long term. It’s because OEM spark plugs last longer and save you more fuel.

The Bottom Line

OEM spark plugs are the cheaper, safer, and more effective solution than aftermarket spark plugs.