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NGK Iridium IX Spark Plugs

NGK Iridium IX. Made in Japan. Certified Authentic. Look for security laser seal or your money back.

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Designed specifically for the performance enthusiast, Iridium IX offers extreme ignitability, improved throttle response and superior anti-fouling.

  • Fine Iridium tip ensures high durability and a consistently stable spark
  • Iridium alloy has extremely high melting point, perfect for today’s high-tech, high-performance engines
  • Trivalent metal plating provides superior anti-corrosion and anti-seizing properties
  • Outstanding acceleration, high fuel efficiency, and durability
  • Ultimate design, technology, and performance



1. Anti-seize

NGK spark plugs feature what is known as trivalent plating. This silver-or-chrome colored finish on the threads is designed to provide corrosion resistance against moisture and chemicals. The coating also acts as a release agent during spark plug removal. NGK spark plugs are installed at the factory dry, without the use of anti-seize. NGK tech support has received a number of tech calls from installers who have over-tightened spark plugs because of the use of anti-seize. Anti-seize compound can act as a lubricant altering torque values up to 20 percent, increasing the risk of spark plug thread breakage.

2. Corona stain

Corona stain is observed as a light brown or tan discoloration above the hex (located on the ceramic body of the spark plug). Corona stain is created by oil or dirt particles surrounding the spark plug. Spark plugs create a high amount of static electricity as they fire, attracting these particles to the exposed ceramic between the plug boot and the hex. Corona stain is completely normal and should not be mistaken for exhaust gas blow-by or broken seals inside the spark plug.

3. Gapping fine-wire spark plugs

In the late 1980s, when fine-wire spark plugs first appeared, installers used incorrect gap tools and procedures resulting in bent or broken-off firing electrodes. As a result, many people assumed that one cannot adjust the gap on a precious metal plug. While most NGK spark plugs are pre-gapped, there are instances where the gap requires modification. NGK recommends a wire-style or feeler gage gap tool, which can adjust the gap without prying against the center electrode. NGK also recommends adjusting the gap no more than +/- 0.008” from the preset gap.

4. Torque 

Torque is critical in the plug’s ability to dissipate heat and perform properly. Always follow the manufacturer’s recommended torque specification. An under-torqued spark plug can lead to excessive vibration and improper heat dissipation, causing spark plug and/or engine damage. An over-torqued spark plug may cause thread damage or breakage, or compromise internal seals within the spark plug, leading to improper heat dissipation or exhaust gas blow-by.

5.“Copper plugs”

“Copper spark plugs” is a term mistakenly used for a standard material spark plug. A standard material spark plug traditionally uses a nickel-alloy outer material fused to a copper core. Almost all spark plugs use a copper core center to conduct the electricity, jump the gap, and promote heat dissipation. However, as an outer electrode material, copper would not be a good choice, as it is soft and has a low melting point (resulting in a plug that would last minutes, not miles). Nearly all NGK spark plugs, including precious metals iridium and platinum, have a copper core. When one talks in terms of nickel alloys, platinum and iridium, one is referring to its durability, or how long a spark plug will last before it needs to be replaced. However, when one talks about copper, he or she is referring to its ability to conduct electricity that is needed to fire across the gap and ignite the air-fuel mixture.


Since 1936, NGK Spark Plugs has been the world leader in technology, innovation, and world-class quality in the design of spark plugs and oxygen sensors. Our commitment to excellence continues to be the driving force behind the company’s advanced research and development programs. Ceramics, at the core of superior spark plug technology, spawned the creation of NTK Technical Ceramics. Additional lines of products followed; NGK Wire Sets, NTK Oxygen Sensors, NTK Knock Sensors and a variety of other NTK sensors. Today, the company manufactures spark plugs and oxygen sensors for virtually every automotive manufacturer in the world, and has set some groundbreaking industry firsts along the way including:

NGK Headquaters

  • Introduction of copper core spark plugs to the consumer market.
  • The pioneering development of new ceramics and its revolutionary application to integrated computer circuitry.
  • Introduction of the "V-Groove" spark plug, which proved ideal for clean-burning, lower-emission engines.
  • Introduction of iridium spark plugs for OEM and performance markets.
  • Continuing environmental and anti-pollution efforts.

Committed to Excellence

NGK has built a reputation for quality and reliability. With state-of-the-art manufacturing, inventory and distribution facilities in Irvine, California; Sissonville, West Virginia; Chicago, Illinois and ISO 14001 & ISO/TS 16949 certification, NGK is dedicated to providing our customers with the finest products and service possible.

NGK has built a reputation for quality and reliability; manufacturing spark plugs for virtually every automotive, motorcycle, marine and small engine application. With state-of-the-art manufacturing, inventory and distribution facilities, NGK is dedicated to providing customers with world-class products and services. NGK has built a reputation for quality and reliability, and a commitment to excellence continues to be the driving force behind the company’s advanced research and development programs.

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