There will inevitably come a time in your Z-Car ownership when you will need to replace your spark plugs. Some decide to replace their plugs fairly often, every 10,000 miles or so. This is fairly normal for a 30+ year old car like the 300ZX, but you can likely get away with waiting a bit longer than that if you wish. Obviously, if you experience signs of spark plug failure, it is likely time to replace your plugs regardless. On a Z31 or Z32 300ZX, you should always purchase NGK spark plugs, but the actual plug type depends on a few factors:
Z32 Spark Plugs
Non-Turbo: NGK PFR6G-11
Turbo: NGK IFR6E-11 (6741)
Z31 Spark Plugs
Non-Turbo: NGK BCPR6ES-11
Turbo: NGK BCPR6E-11
If you wish to purchase online, you can buy these directly through ZCarGuide. Although all of these spark plugs come pre-gapped, you will want to make sure you double check the gaps with a spark plug gap gauge that can accommodate the gap range we are looking for, such as this one.
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|Model||Spark Plug Gap|
|Z31 Turbo||1.0mm-1.1mm, 0.039-0.043in|
|Z31 Non-Turbo||1.0mm-1.1mm, 0.039-0.043in|
To remove, you will want to use a 21mm or 13/16in deep/sparkplug socket, such as this one. You may find that some plugs do not look all that worn or in need of replacement, but in general it is always a good idea to replace all 6 at once with brand new plugs. If you choose to use anti-seize, be careful not to apply too much. Lightly oiling the threads should be enough though.
For more information about removing your old plugs and reinstalling new ones, we recommend the YouTube video embedded below: