NGK Laser Iridium SILFR6A11 Spark Plug
Priced as of May 27, 2026
4.6(113 ratings)Buy on AmazonSaved to your guest loadout. Sign up to also save to your Cabinet (consumables) or Kit (tools you own).
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Prices may varyThe Podium · Top 3 in Spark Plug
See the full ranking →This product ranks #3 of 8 in Spark Plug.
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- Bronze · #3You're hereNGKLaser Iridium SILFR6A11 Spark PlugCCT 7.5
CarCareTruth's Analysis
Last reviewed May 27, 2026
TL;DR NGK is the OE supplier for Subaru EJ255/EJ257 engines; this iridium plug cross-references dealer parts 22401AA670 and 22401AA720, ships pre-gapped to 1.1mm, and is rated 100,000 miles.
What it is and how it performs
Iridium center electrode with platinum-tipped ground and a silver-alloy laser weld (SILFR designation). Heat range 6, M14×1.25 thread, 26.5mm reach, gasket seat, factory gap 1.1mm matching Subaru OEM spec for the EJ255 and EJ257. NGK supplies this plug to Subaru dealer channels as 22401AA670 and 22401AA720, covering WRX, STI, Legacy GT, Outback XT, and Forester XT from 2004 to 2014. Center electrode tip diameter is not disclosed in the product listing. Community reports no heat-range complaints on any listed application; gap is confirmed factory pre-set.
Who should buy this — and who should skip it
Right pick for a 2004-2014 Subaru EJ255 or EJ257 on a 100,000-mile interval; OEM provenance and dealer-PN cross-reference confirmed. Skip if the engine needs a colder heat range or tighter gap for high-boost operation.
Safety and environmental impact
No chemical exposure from the plug itself. Iridium and platinum tips carry small precious-metal mass per plug, partially offset by the long service interval. Steel shell is recyclable as ferrous scrap; the alumina-ceramic insulator goes to landfill.
From the manufacturer
Marketing copy from NGK, via Amazon. Not editorial.
- •Original Equipment
- •Item Package Dimension: 3.66L x 0.94W x 0.90H inches
- •Item Package Weight - 0.11 Pounds
- •Item Package Quantity - 1
- •Product Type - SPARK PLUG
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Manufacturer images
Manufacturer specifications
- Brand
- NGK
- Core Material
- Iridium
- Thread Size
- 1.25mm
- Top Material Type
- Ceramic
- Vehicle Service Type
- Car, Truck
- Brand Name
- NGK
- Manufacturer Part Number
- SILFR6A11
- Global Trade Identification Number
- 00087295154687
- UPC
- 087295154687
- OEM Equivalent Part Number
- 5468
- Model Number
- SILFR6A11
- Unit Count
- 1.0 Count
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Top Amazon review
↗External — Amazon's most-helpful review for context.
kisashi tune up
Needed these for suzuki for 60k and my other suzuki at 90k service. Cars both started and run so they work good and obviously held up for 55k and 92k miles already so should have another 5 years plus. Quick shipping and fair price.