{"product_id":"ngk-iridium-ix-spark-plug-cr9eix-4-pack-fine-wire-iridium-tip-oem-fit","title":"NGK Iridium IX Spark Plug CR9EIX 4-Pack — Fine-Wire Iridium Tip, OEM Fit","description":"\u003cp\u003e\u003cstrong\u003eNGK CR9EIX Iridium IX spark plugs are OEM-grade ignition components engineered to deliver reliable starts and consistent combustion for compatible gasoline engines.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eThese four NGK CR9EIX plugs (OEM part #3521) are high-performance iridium-tipped replacements designed for direct fitment where NGK specifies CR9EIX. They pair a fine-wire iridium center electrode with durable construction to help preserve ignition performance, reduce misfires, and maintain throttle response over long service intervals. This listing covers a 4-pack ideal for multi-cylinder engines and routine maintenance jobs.\u003c\/p\u003e\n\n\u003ch3\u003eHow do these iridium plugs affect engine starting and idle?\u003c\/h3\u003e\n\u003cp\u003eIridium’s hard, wear-resistant tip maintains a sharp electrode profile much longer than standard plugs, promoting reliable spark across many miles. That consistent spark improves cold starts and keeps idle smooth as electrodes wear more slowly.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eFine iridium center electrode for concentrated spark energy\u003c\/li\u003e\n  \u003cli\u003eStable idle through extended service life\u003c\/li\u003e\n  \u003cli\u003eGood cold-start performance under typical conditions\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWill NGK CR9EIX plugs fit my vehicle and how do I confirm compatibility?\u003c\/h3\u003e\n\u003cp\u003eThese are OEM NGK replacement plugs (part #3521) so they will fit applications that call for CR9EIX or the equivalent NGK number. Always cross-check your vehicle’s service manual or an NGK parts lookup to confirm gap, thread reach, and heat range match your engine.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eOEM part number: 3521 for exact cross-reference\u003c\/li\u003e\n  \u003cli\u003eVerify thread size, reach, and heat range with factory specs\u003c\/li\u003e\n  \u003cli\u003eFour plugs included for most multi-cylinder engine services\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat maintenance interval and handling tips should I follow?\u003c\/h3\u003e\n\u003cp\u003eIridium plugs generally offer longer intervals than conventional copper plugs, but replacement should follow manufacturer recommendations or inspection results. Install with a torque wrench to the correct specification and use anti-seize only if the vehicle maker advises it; improper torque or lubrication can affect performance.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eFollow vehicle OEM mileage\/time replacement intervals\u003c\/li\u003e\n  \u003cli\u003eTorque to factory specification at installation\u003c\/li\u003e\n  \u003cli\u003eInspect for fouling, electrode wear, or abnormal deposits during service\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow do NGK CR9EIX plugs compare in longevity and performance?\u003c\/h3\u003e\n\u003cp\u003eCompared with standard plugs, iridium-tipped plugs like the CR9EIX typically exhibit longer effective life and retain ignition efficiency as electrodes wear more slowly. They are a common upgrade where longevity, stable combustion, and dependable starting are priorities.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eLonger electrode life due to durable iridium tip\u003c\/li\u003e\n  \u003cli\u003eConsistent combustion quality across service life\u003c\/li\u003e\n  \u003cli\u003eOEM-level fit and finish for straightforward replacements\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho is this for: Mechanics, DIY enthusiasts, and vehicle owners seeking an OEM NGK replacement with improved electrode longevity will find the CR9EIX 4-pack suitable. It’s intended for engines specified to use this NGK type — ideal for routine tune-ups, pre-trip checks, or restoring consistent ignition where plug wear or misfires were apparent.\u003c\/p\u003e\n\n\u003cp\u003eProduct details: NGK OEM part number 3521; sold as a 4-pack; genuine NGK replacement spark plug; iridium center electrode. Use official NGK cross-reference tools or your vehicle’s service manual to confirm fitment before purchase.\u003c\/p\u003e\n\u003csection class=\"product-faq-snippet\"\u003e\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Is this the OEM NGK part number for CR9EIX?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes — this listing is for the genuine NGK OEM part #3521 corresponding to CR9EIX.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: How many plugs come in the package?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: The product is sold as a 4-pack, suitable for most four-cylinder tune-ups.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"NGK","offers":[{"title":"Default Title","offer_id":55168557908311,"sku":"B004SKYAWM","price":48.77,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1050\/1524\/7191\/files\/ngk-cr9eix-front-box-packaging.jpg?v=1790408170","url":"https:\/\/britishgarage.co.uk\/products\/ngk-iridium-ix-spark-plug-cr9eix-4-pack-fine-wire-iridium-tip-oem-fit","provider":"British Garage","version":"1.0","type":"link"}