Top 3 Best Spark Plugs for RX8 [Rotary Engine] Review in 2021

Best Spark Plugs for Mazda Rx

Spark plugs are a precious part of every vehicle. Your Mazda RX-8 might require a change in the spark plugs as it has been a while since you’ve changed it. Changing it from time to time is vital for the betterment of the vehicle. However, you might get confused while choosing the Best Spark Plugs for Mazda Rx as there are so many sparks plugs up for grabs. Choosing the wrong one might result in damage to your vehicle’s engine. Here is a list of spark plugs that are right for the Mazda RX-8 for your convenience.

What is the best/or recommended OEM spark plugs on a Mazda RX-8?

Among the spark plugs obtainable and correct for the Mazda RX-8, NGK Laser Iridium Racing Spark Plugs RE7CL RE9BT Mazda RX-8 1.3 R2 might be the best one yet. The set comprises four items: NGK Laser Iridium RE7C-L, RE9B-T, RE7CL RE9BT Mazda RX-8 RX8 Leading Trailing, NGK 6701, NGK 6700 spark plugs with slightly different specifications. Spark plugs are all pre-gapped and original OGK, so they just fit right in. They are even of prolonged life with a great configuration. They can also perform a comprehensive set of functions without showing many complexities. So, this one takes the crown.

Top 3 Best spark plugs for rx8 in 2021

Name of the productFeatures
NGK Laser Iridium Racing Spark PlugsSeat type is Gasket Extra durable Comes with 4 items
NGK RE9B-T Laser Iridium Spark PlugIridium Electrode with Copper Core Backside Platinum WeldedPre-gapped at 0.048”The Heat Range is 9
NGK (6700) RE7C-L Laser Iridium Spark PlugIridium Electrode with Copper CorePre-gapped at 0.043”The Heat Range is 7Comparatively Cheaper

3 Best Spark Plugs for RX8 Review in 2021

#1. NGK Laser Iridium Racing Spark Plugs

NGK Laser Iridium Racing Spark Plugs is composed of four original NGK spark plugs. With a machine-rolled thread and longer insulator noses, these spark plugs feature the distinctive details that make the spark plugs live longer. They are reliable and can perform various functions while fitting easily onto the vehicles, especially race cars like Mazda RX-8.

Among the available spark plugs, this kit is composed of the best NGK components for a Mazda RX-8. NGK Laser Iridium RE7C-L, RE9B-T, RE7CL RE9BT Mazda RX-8 RX8 Leading Trailing, NGK 6701, NGK 6700 spark plugs are the components in this set. All of the products are of great configuration while performing the functions comfortably.

Technical Features:

  • Manufacturer: NGK
  • Material: Iridium
  • Pre-gapped: Yes
  • Seat Type: Gasket


Items: The set NGK Laser Iridium Racing Spark Plugs RE7CL RE9BT Mazda RX-8 1.3 R2 consists of 4 spark plugs produced by NGK. The items are NGK Laser Iridium RE7C-L, RE9B-T, RE7CL RE9BT Mazda RX-8 RX8 Leading Trailing, NGK 6701, NGK 6700 spark plugs. All of the items have different specifications according to the need and a very well built body.

Specifications: This kit, full of different spark plugs, is formed of robust spark plugs. With laser welded tips, the electrode is of Iridium with a copper core. The thread is machine-rolled, and the seat type is the gasket. All of the spark plugs are pre-gapped.

Functions: Four beautiful spark plugs assemble the kit to perform a good amount of parts. With the copper core and iridium tip, it can easily tolerate heat and use less voltage even. The insulators are longer, and corrugated ribs are on them to prevent fouling and flashovers.


  • NGK Laser Iridium Racing Spark Plugs RE7CL RE9BT Mazda RX-8 1.3 R2 is made of 4 spark plugs. All of them can perform well and save horsepower of the vehicle while using less voltage.
  • This kit is full of efficient and durable items. For example, the enhanced spark plugs can efficiently work fine in adverse situations, iridium electrodes and copper core easily can remove heat.
  • The spark plugs in this set have an elegant, rugged body. As a result, they can perform their functions well while preventing flashovers, corrosion, and whatnot.
  • With the laser-welded tip and being fine wired, the spark plugs in this set can create stable and consistent sparks effortlessly.


  • You get four items in this kit with different gaps. The extra ones are left there, and the kit’s price might seem a bit pricey, but it consists of 4 distinguished spark plugs.

#2. NGK RE9B-T Laser Iridium Spark Plug

NGK RE9B-T Laser Iridium Spark Plug can execute its expected functions with the ability to last long even in highly unfavorable situations while making a place in the best spark plugs for a rotary engine. With slanted ground electrodes and corrugated ribs on the insulator, the spark plug comprises the little details that make it long-lasting and work well.

This durable spark plug has an iridium center electrode with a copper core allowing performing effortlessly, saving and increasing horsepower at the same time. Furthermore, it is the best spark plugs for rotary engines that have laser-welded fine tips with longer insulator noses that prevent fouling while producing steady sparks.  In addition, this pre-gapped and 5k Ohm resistor valued spark plug has a platinum disc welded in the back for persistence.

Technical Features

  • Center Electrode Core Material: Copper Core
  • Resistor Value: 5k Ohm
  • Pre-gapped: 0.048”
  • Heat Range: 9
  • Ground Configuration: Slant


Build: NGK RE9B-T Laser Iridium Spark Plug has a fantastic build with a copper core and iridium electrode, making it as long-lasting as possible. This stable spark plug is pre-gapped at 0.048” in with a gasket seat and 14 mm thread.

Qualities: This enhanced version of the spark plug has different qualifications. The longer insulators have corrugated ribs, which prevent fouling and flashovers. The triple gasket seal helps to remove the gas leakage. The tip is laser welded and platinum disc placed in the back, resulting in longer life and better sparks.

Performance: The performance is the deal-breaker in the case of many spark plugs. But in this case, you get faster starts, better acceleration, and better fuel economy with lesser emissions. Trivalent metal plating is also present in this advanced spark plug for averting seizing properties and corrosion.


  • NGK RE9B-T Laser Iridium Spark Plugs have an advanced built for the technologically upgraded vehicles.
  • This suitable spark plug can quickly survive in the utmost unfavorable circumstances, and functions just like this spark plug is expected to due to Iridium electrode with a copper core.
  • With a copper core iridium center electrode, the platinum disc is present in the sparkplug’s back. This configuration is rare and makes it very efficient on the spark plug.
  • NGK RE9B-T Laser Iridium Spark Plugs fit just right in, especially in the race cars like Mazda RX-8. The machine rolled thread makes installing a lot easier.


  • This efficient spark plug can perform a good amount of functions. But compared to the other spark plugs available, the spark plug is a bit pricey.

#3. NGK (6700) RE7C-L Laser Iridium Spark Plug

NGK (6700) RE7C-L Laser Iridium Spark Plug can perform a set of functions without showing much problem or complexities. It has been successful in achieving the satisfaction of the customers over the years. This fine spark plug with a slanted ground electrode can survive for 100k miles.

The long-lasting spark plug has a slanted ground platinum electrode with an iridium center electrode with a copper core. This pre-gapped spark plug with triple gasket seals has a pure alumina silicate ceramic insulator with corrugated ribs preventing fouling, gas leakage, and flashovers. Laser-welded fine wire spark plug has better heat transfer, fuel efficiency, and lesser emissions, ensuring a longer life. With a machine-rolled thread, the heat range is 7 and the resistor value is 5k Ohm.

Technical Features:

  • Center Electrode Material: Iridium
  • Pre-gapped: 0.043”
  • Seat Type: Gasket
  • Heat Range: 7
  • Longevity: 100k Miles


Specifications: NGK (6700) RE7C-L Laser Iridium Spark Plug is one of the well-structured spark plugs available in the market. This sturdy spark plug consists of an iridium center electrode with a copper core resulting in heat removal. The ground material is platinum and is slanted. The gap is 0.043″ with a gasket seat and solid terminal.

Attributes: The enhanced spark plug has many qualities. It has a copper core aiding heat transfer. Ceramic insulator of pure alumina silicate with corrugated ribs helps prevent fouling, flashover, and even greater strength. For supplying anti-seize properties and preventing corrosion, trivalent metal plating is present.

Performance: With a 5k Ohm resistor value, this beautiful spark plug can efficiently execute a great variety of functions. The heat range is seven and can easily tolerate heat because of copper core and iridium material. Consistent and steady sparks are ensured by the laser-welded iridium tip while improving fuel economy.


  • NGK (6700) RE7C-L Laser Iridium Spark Plug can perform many functions like other spark plugs. In addition, this efficient spark plug’s price is a bit less than the similar spark plugs available.
  • This budget-friendly spark plug works well in high temperatures using less voltage. This improves the fuel economy and increases the horsepower to a certain amount.
  • The user-friendly spark plug with machine-rolled thread can effortlessly be installed into the car’s engine, making it very easy to use.
  • NGK (6700) RE7C-L Laser Iridium Spark Plug can produce stable and steady sparks with quicker starts and acceleration for the laser- welded tip and well-formed body.


  • This budget-friendly option can perform its everyday tasks very quickly. But it has a lesser heat range than the other similar spark plugs available.

When to Change the Spark Plugs on a Mazda RX-8?

It might seem confusing as to when to change, and know that it is that time of the year. Usually, after every 32000 km to 50000 km, i.e., 20000 miles to 53000 miles, you should change spark plugs on a Mazda RX-8. But there can be a situation, too, where your Mazda RX-8 is running roughly or having to get started. So you should get them changed then even if the recommended service interval has not been reached.

What are the Signs of a Bad Spark Plug in an RX-8?

You might be confused about when to understand correctly that the spark plug is wrong but not any other crucial component of the car. However, there should be signs if there is a bad spark plug used. The probable signs are listed below:

  • Reduced Fuel Economy: For a while, it seems like you’ve been using more fuel than you used to before. This might be a sign of a bad spark plug.
  • Hard starts: Previously, you used to spark your Mazda RX-8 in a moment. But recently, it is taking a bit more time than that, and you’re facing trouble to start it. Of course, it also might be a sign of a bad spark plug, but this is caused by other problems, too.
  • Poor acceleration: Your vehicle feels particularly slow than before these days. Bad or dirty spark plugs might be the reason.
  • Rough Idle: This is a problem caused by many other issues in the car, but a lousy spark plug might be the one.
  • Engine Knock: You feel like your engine’s cylinder feels weird. That’s an engine knock, and if this takes place, the spark plug might be the culprit.
  • Engine Misfires: There should be flashing when this happens. You can check the engine light for it. A bad spark plug can cause it.

What kits do you need for Mazda rx8 spark plugs replacement?


How often should I change spark plugs RX-8?

Spark plugs are the essentials of any vehicle, including your Mazda RX-8. The recommended service interval for Mazda RX-8 is after every 32000 km to 50000 km or 20000 miles to 53000 miles. But, if your vehicle is showing problems in starting or running rough, you should change the spark plugs. The problem may arise before reaching the service interval. We would advise you to still get them changed.

How many spark plugs does a Mazda Rx8 have?

Spark plugs might be changed after every service interval or if there is any trouble showing in your vehicle. The question might come up as to how many spark plugs are required. For example, a Mazda RX-8 has a rotary engine. So, it requires four spark plugs; 2 spark plugs per rotor, a leading, and a trailing spark plug. You can learn more about it with your advisers.

How much does it cost to maintain an Rx8?

Maintaining an RX-8 might seem like a costly deal, but in reality, it is not. If there are no extra complications shown in the car that can be done by looking after it and maintaining the service intervals, the cost is very average, and in some cases, very low. But it depends on how you look after it and change parts in it like spark plugs.

Do you gap rx8 spark plugs?

0.048″ is the ideal gap size for a Mazda RX-8, but it might vary depending on the specification of the car. The spark plugs should be pre-gapped in the precise size. You can easily find spark plugs for your RX-8 in the market. NGK manufactures precisely gapped spark plugs for cars, like the Mazda RX-8. So, it would help if you didn’t have to be worried about gapping the spark plugs yourself.

How do you remove spark plugs from a Mazda Rx8?


Spark plugs are, undoubtedly, a significant part of your Mazda RX-8 to keep it running smoothly. There might be many spark plugs available, but these three spark plugs; NGK Laser Iridium Racing Spark Plugs, NGK RE9B-T Laser Iridium Spark Plug, and NGK (6700) RE7C-L Laser Iridium Spark Plug, are the best ones out there. They can do a vast set of functions but have different advantages like heat range, price, build, etc. It depends on your needs and likings in the end.

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