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Combustion engines create a mixture of air and fuel that must be ignited to provide power to the vehicle, and spark plugs provide that trigger. Spark plugs are designed to set off this air and fuel mixture, allowing the engine to generate enough power to move the vehicle. Despite the small size of these components, without spark plugs, the vehicle would not be leaving the driveway under its own power. A brand new vehicle may not need new spark plugs for 50,000 to 100,000 miles, but when the existing spark plugs start to fail, the vehicle will begin to show signs, such as rough idling sounds, knocking engine noises, trouble starting the car, bad fuel economy, and engine misfires. In order to restore healthy operation to the engine, it’s necessary to invest in new spark plugs, and this guide will help you learn about the best spark plugs for your vehicle.
- Best overall: Autolite Iridium XP Spark Plugs
- Best value: NGK Iridium Spark Plugs
- Best platinum: Bosch 4417 Platinum+4 FGR7DQP Spark Plug
- Best copper: E3 Powersports Spark Plug
- Best double iridium: BOSCH Fine Wire Double Iridium Spark Plug
How we chose the best spark plugs
In order to select a list of the best plugs, it was necessary to conduct extensive research into a broad pool of products to find the top options based on several key product specs. The first factor that was taken into consideration was the type of plug, differentiated by the material. Premium iridium products were preferred, but not all vehicles are made to use this type, so the top list also makes room for alternate types, including copper, platinum, and double iridium.
The hex size, gap, and expected life of the products were also reviewed to find the best plugs for the vehicle. Additionally, the listed heat range for each spark plug was noted and compared against other products using a simple heat range cross-reference chart to get a clear idea of the performance of each product. Using this information, the top options were selected for this list of the best spark plugs.
The best spark plugs: Reviews & Recommendations
The list below comprises the top products based on thorough research and review. Take a look at this selection to find the best spark plugs for your vehicle.
Best overall: Autolite Iridium XP Spark Plugs
Best overall
Autolite Iridium XP Spark Plugs
Why it made the cut: Replace old, worn plugs with these high-efficiency iridium ones by Autolite.
Specs
- Type: Iridium
- Hex Size: ⅝-inch (16mm)
- Life: 100,000 miles
- Gap: 0.044 inches (1.1mm)
Pros
- Lasts for up to 100,000 miles
- Iridium design is made for optimal performance and fuel efficiency
- High-alumina ceramic insulator for increased strength
- Built-in platinum-protected ground wire and V-trimmed ground electrode
Cons
- Nickel top can negatively affect performance
Vehicles are made up of a wide variety of parts that work together to make the car or truck function. If any parts are worn out or beginning to show signs of failure, then this can impact the operation of the vehicle, leading to minor issues that can grow into more serious problems if the parts are not replaced. This can be commonly seen when the tread on tires starts to wear down.
Similarly, spark plugs can wear out over time, leading to ignition problems, reduced fuel efficiency, and engine issues, so it’s important to replace old, worn ones as soon as possible. This set of iridium plugs is a great choice for compatible vehicles because they can last for up to 100,000 miles before they need to be replaced.
The iridium design increases engine performance and fuel efficiency for the vehicle, though it should be noted that the performance may be slightly reduced by the nickel top. This is made up for with the inclusion of platinum-protected ground wires and V-trimmed ground electrodes, which greatly improve efficiency and ignitability. Additionally, the plugs have a high-alumina ceramic insulator that increases the strength and durability.
Best value: NGK Iridium Spark Plugs
Best value
NGK Iridium Spark Plugs
Why it made the cut: Take advantage of this six-plug value pack to get new iridium plugs for compatible vehicles.
Specs
- Type: Iridium
- Hex Size: ⅝-inch (16mm)
- Life: 50,000 miles
- Gap: 0.043 inches (1.1mm)
Pros
- Anti-corrosion and anti-seizing properties
- Superior strength and heat transfer
- Iridium design offers high performance and efficiency
- Triple-sealed to prevent leakage
Cons
- Short 50,000-mile lifespan
Replace old or faulty plugs with this set of six iridium ones by NGK. The six-plug value pack is a great way to get high-performance iridium spark plugs without overspending. Each plug is made with trivalent metal plating, which provides superior anti-corrosion and anti-seizing properties, ensuring that the plug functions effectively for the duration of its lifespan.
The plugs also have pure alumina silicate ceramic insulators, which improve strength and heat transfer, and a copper core intended to aid in heat removal. Additionally, the plugs are triple-sealed to prevent leakage so drivers can feel confident in the durability of these replacement parts for their vehicle. However, these spark plugs are only rated for about 50,000 miles before they need to be replaced.
Best platinum: Bosch 4417 Platinum+4 FGR7DQP Spark Plug
Best platinum
Bosch 4417 Platinum+4 FGR7DQP Spark Plug
Why it made the cut: Opt for these platinum plugs for reliable performance and affordable cost.
Specs
- Type: Platinum
- Hex Size: ⅝-inch (16mm)
- Life: N/A
- Gap: 0.063 inches (1.6mm)
Pros
- Yttrium alloy ground electrodes reduce wear and oxidation
- Last two times longer than standard copper spark plugs
- Multiple spark paths increase spark power and longevity
- Enhanced ground electrodes improve combustion efficiency
Cons
- Performance levels may not be as high as iridium spark plugs
Some manufacturers are wary about providing specific lifespans for spark plugs and similar automotive products due to the range of factors that can affect the overall life of these components. With this in mind, Bosch does not state a specific lifespan but does note that these plugs will typically last about two times longer than standard copper ones.
Additionally, these platinum plugs may not have the same high level of performance as iridium products, but the cost is generally lower, and platinum plugs still outperform copper products. These Bosch plugs boast yttrium alloy ground electrodes, which reduce gap wear and oxidation, as well as improving combustion efficiency. Also, the plugs feature multiple spark paths that allow them to increase the spark power output and spark longevity, improving the reliability of the ignition system.
Best copper: E3 Powersports Spark Plug
Best copper
E3 Powersports Spark Plug
Why it made the cut: Older cars and some motorcycles are made for use with copper plugs, like this product from E3 Spark Plugs.
Specs
- Type: Copper
- Hex Size: ⅝-inch (16mm)
- Life: 100,000 miles
- Gap: 0.043 inches (1.1mm)
Pros
- Dual-leg ground electrode design helps facilitate heat transfer
- Long 100,000-mile lifespan
- Unique side wire increases power and reduces fuel consumption
- Suitable for use in cars, snowmobiles, bikes, and more
Cons
- Only one spark plug in the package
Copper spark plugs are still widely in use for a range of vehicles. This plug by E3 Spark Plugs is made for cars, trucks, snowmobiles, motorcycles, boats, ATVs, and even some chainsaw or lawnmower engines. Before investing in this copper plug, check the manufacturer’s information to determine if the spark plug is compatible with the specific engine.
This plug is rated for 100,000 miles before it needs to be replaced. The long life and increased power are primarily due to the unique side wire design, which also helps to reduce fuel consumption and improve hydrocarbon emissions. The spark plug also features a ground electrode with two legs to help facilitate heat transfer and withstand high vibrations. However, it should be mentioned that only one plug is included in this package, so you may need to purchase more than one depending on the engine’s needs.
Best double iridium: BOSCH Fine Wire Double Iridium Spark Plug
Best double iridium
BOSCH Fine Wire Double Iridium Spark Plug
Why it made the cut: When standard iridium plugs aren’t quite enough, double iridium plugs may be the solution to improve performance, fuel efficiency, and reliability.
Specs
- Type: Double Iridium
- Hex Size: ⅝-inch (16mm)
- Life: N/A
- Gap: 0.043 inches (1.1mm)
Pros
- Increased durability due to 360-degree continuous laser welding
- Iridium firing pin and ground electrode offer superior performance
- Lasts four times longer than standard copper spark plugs
- Pre-gapped design with nickel-plated threads for quick installation
Cons
- Package only comes with one spark plug
In most cases, iridium spark plugs are the top option, offering superior performance and efficiency, but if a standard iridium plug isn’t enough, then this double iridium plug may be a suitable replacement for compatible vehicles. The double iridium design includes an iridium firing pin and an iridium ground electrode, which greatly improves the performance of these components.
This plug also comes pre-gapped for easy installation and features a copper core to increase heat resistance during use. Additionally, the plug is made with a fine wire design that requires up to 24 percent less voltage for ignition. It also boasts a 360-degree continuous laser welding design for enhanced durability. Though, it should be noted that the package only includes one plug, so you may need to purchase more than one package to complete the replacement.
Things to consider when buying the best spark plugs
Purchasing spark plugs is a good idea if the current set of plugs in the vehicle has started to show signs of significant wear. However, it’s important to find the right plugs for the vehicle, so before shopping around for new products, it’s necessary to check the manufacturer’s directions to determine the correct spark plug type, hex size, heat range, and gap for the vehicle.
Type
Spark plugs are generally available in the following five types, each differentiated based on the material:
- Iridium spark plugs are the go-to option for performance cars because they have high reliability, performance, and life span. These plugs also improve fuel efficiency, but the material quality of iridium plugs can increase the cost of these products.
- Platinum spark plugs are less costly than iridium plugs and still boast a considerably higher performance, fuel efficiency level, and lifespan than copper plugs. This combination of affordability and superior performance makes platinum plugs one of the more popular options.
- Copper spark plugs are the most inexpensive choice, though they are also the least reliable. However, many older vehicles require copper plugs to operate with optimal performance, so make sure to check the needs of the specific engine before purchasing replacements.
- Double platinum spark plugs are essentially a reinforced version of regular platinum plugs, allowing these products to improve efficiency and performance. Though, the drawback is the double platinum plugs cost more than standard platinum plugs.
- Double iridium spark plugs are made for high-performance vehicles. These are the most costly option available, but they significantly improve over other options, with a lifespan that typically lasts four times longer than copper plugs.
Hex size
When selecting a new set of spark plugs for the vehicle, it’s essential to find products that fit the vehicle. With this in mind, you need to check the vehicle manual or review the manufacturer’s website to determine the hex size compatible with the car, truck, or van. Alternatively, you can remove one of the existing plugs and take it to a local automotive store to find a suitable replacement.
The hex size is one measurement you must pay close attention to to find compatible replacement parts. This measurement is generally noted in inches, though it may also be listed in millimeters. Typically, you can find this information on the product package, though if it isn’t noted, you will need to look up the product specs before purchasing the new spark plugs.
Heat range
Spark plugs generally operate within a specific heat range, though the way this range is communicated in the product specs can get confusing because different manufacturers represent this factor in different ways. Ideally, you want a plug that can get up to the operating temperature as quickly as possible to prevent soot from forming on the plug.
However, you also need to ensure that when you run the vehicle for extended periods, the plugs will not heat up beyond the allowable operating temperature. Essentially, you want to find plugs that heat up quickly but operate at a cool enough temperature to avoid overheating. The best way to do this is to check the existing plugs and the manufacturer-provided information to find compatible components.
Gap
Another factor to consider when looking for new plugs is the gap. Spark plugs are made with a calculated spark plug gap that can be adjusted using a gapper tool. However, many plugs are sold with a pre-set gap, so if you find a product with the right gap size, you may be able to replace the existing plugs without using a gapper tool.
For cars and similar vehicles, spark plug gaps generally range between 0.024 inches and 0.071 inches. These numbers can be provided in millimeters, ranging from 0.6mm to 1.8mm. Before purchasing new plugs for the car, make sure that the gap falls into the specified range for the vehicle’s engine. If the gap is slightly off, you may be able to use a gapper tool to adjust the gap for the correct fit, though this is only recommended for experienced automotive DIYers and professionals.
FAQs
Generally, copper spark plugs should be changed about once every 30,000 to 50,000 miles, while platinum and iridium spark plugs can last substantially longer. For cars that use platinum or iridium spark plugs, plan to replace these parts about once every 60,000 to 150,000 miles.
When the spark plugs are not functioning properly, there are a few signs that can serve as an indicator. The most common signs include issues starting the car, rough idling, slow or stilted acceleration, bad fuel economy, engine knocking, and misfires.
Automotive DIYers who already tackle car maintenance projects, like replacing the brakes or changing the oil, should be able to replace the spark plugs in the vehicle without professional help. However, for those who have never looked under the car’s hood, it’s best to entrust the job to an experienced individual.
Final thoughts on the best spark plugs
- Best overall: Autolite Iridium XP Spark Plugs
- Best value: NGK Iridium Spark Plugs
- Best platinum: Bosch 4417 Platinum+4 FGR7DQP Spark Plug
- Best copper: E3 Powersports Spark Plug
- Best double iridium: BOSCH Fine Wire Double Iridium Spark Plug
Vehicles are necessary for driving kids to school, commuting to work, picking up groceries, heading out on a road trip, and many other purposes. The driver and passengers entrust their safety and security to the vehicle during use, so it’s essential to ensure the vehicle is in good working order before starting the ignition. With this in mind, replacing old or worn spark plugs as soon as possible is important.
Making this change will reduce the chance of ignition problems, engine issues, and lower fuel efficiency, allowing the driver to feel confident in the safety and functionality of the vehicle. When replacing spark plugs, make sure to check the manufacturer’s information to determine the correct spark plug type, gap, hex size, and heat range for the vehicle.
