What Are The Best Spark Plugs For A Mazda RX-8?

It is incredibly important that you use the correct spark plugs in your Mazda RX-8 and replace them at the recommended service interval or before. If the spark plugs fitted to your Mazda RX-8 are incorrect it can lead to poor performance and possibly even engine damage. We have put together a quick guide on the correct spark plugs for an RX-8 and when to change them. Carry on reading below:

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

Reduced fuel economy – If you find that you are making more frequent trips to the petrol/gas station in your RX-8 it may be a sign of dirty or fouled spark plugs.

Hard starts – Are you having trouble starting your Mazda RX-8? While this issue can be caused by a number of different problems, it may be a sign that your RX-8’s spar plugs are in a bad way. If the spark plugs can’t produce a spark you won’t be going anywhere!

Poor acceleration – If your RX-8 feels particularly slow, bad spark plugs could be the culprit. Dirty or fouled spark plugs can lead to a poor-quality spark, which will lead to sluggish performance.

Rough Idle – Once again this problem can be caused by several different issues, but bad spark plugs are often a common culprit.

Misfires – This is a very common issue on Mazda RX-8s and is usually a sign that the spark plugs and coils need to be replaced (the stock ignition system may need to be replaced as well, but start with the spark plugs).

Best Spark Plugs for a Mazda RX-8?

It is always recommended that you go with OEM spark plugs on a Mazda RX-8, unless you have a turbocharged or supercharged vehicle. Unlike on a conventional engined car, you will need two sets of spark plugs for the rotary engine inside the RX-8. They are as follows:

NGK RE9B-T – (trailing / top plugs)

NGK RE7C-L – (leading / lower plugs)

When you are changing the spark plugs remember to check the spark plug wires to make sure they are in good condition. The appearance of a spark plug can tell you a lot of information about an engine and how it is running. To find out more about this check out this spark plug analysis guide.

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

It is recommended that you change the plugs on a Mazda RX-8 every 32,000 – 50,000 km (20,000 – 53,000miles). If your RX-8 is running rough or is suffering from any of the problems we listed at the start of this article, it may be a good idea to change the spark plugs even if you have not reached the recommended service interval.

If you are looking to buy a Mazda RX-8 or want to know more about common problems with them, check out our “Mazda RX-8 Buyer’s Guide & History” article.


  • Ben

    From his early days playing the original Gran Turismo and with his Hot Wheels car set, Ben has had a long interest in all things automotive. His first foray into the world of automotive journalism was way back in 2009 and since then he has only grown more interested in the industry. Ben also runs and heads up the video production side of Garage Dreams, focusing on small informative documentaries about some of the world's most legendary cars.

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