{"product_id":"k-n-engine-air-filter-long-life-18-000-mile-replacement","title":"K\u0026N Engine Air Filter: Long Life 18,000 Mile Replacement","description":"\u003cp\u003e\u003cstrong\u003eK\u0026amp;N KNA-2304 is a long-life engine air filter engineered to protect Subaru H4 and H6 engines for up to 18,000 miles with high-efficiency filtration and drop-in OEM fitment.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eThis K\u0026amp;N Advantage Plus replacement air filter swaps directly into the factory airbox on a wide range of Subaru models (Forester, Outback, Legacy, Impreza, WRX, Crosstrek, Levorg and more) and uses premium filter media formulated to balance airflow with particle capture. Compared with many disposable filters rated for 12,000 miles, this filter extends service intervals while meeting or exceeding original equipment specifications for fit and filtration. It’s designed for easy installation and backed by K\u0026amp;N’s parts support and warranty.\u003c\/p\u003e\n\n\u003ch3\u003eHow does this filter protect my engine without reducing airflow?\u003c\/h3\u003e\n\u003cp\u003eThe KNA-2304 uses a premium synthetic or cellulose-blend media (application dependent) that captures fine particles while preserving the airflow your engine needs. Its construction prioritizes both filtration efficiency and low resistance so your Subaru breathes clean air without unnecessary restriction.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eUp to 99% particle capture efficiency to limit contaminant ingress.\u003c\/li\u003e\n  \u003cli\u003eMedia engineered for consistent airflow and engine responsiveness.\u003c\/li\u003e\n  \u003cli\u003eDesigned to meet or exceed OEM specifications for seal and fit.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWill this fit my Subaru and install easily?\u003c\/h3\u003e\n\u003cp\u003eK\u0026amp;N lists the KNA-2304 as compatible with a broad range of Subaru models across model years 2003–2021 for various H4 and H6 engines. The filter is sized to drop into the original factory airbox, so installation usually takes only a few minutes using standard tools or even by hand in many vehicles.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eDirect-fit replacement for many Forester, Outback, Legacy, Impreza, WRX, Crosstrek and Levorg models.\u003c\/li\u003e\n  \u003cli\u003eOEM-style flange and sealing surface to prevent bypass air.\u003c\/li\u003e\n  \u003cli\u003eTypical install time: minutes; no custom modification required.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow often should I replace the K\u0026amp;N KNA-2304 filter?\u003c\/h3\u003e\n\u003cp\u003eThis Advantage Plus filter is rated for 18,000 miles under normal highway driving—about 1.5 years if you average 12,000 miles per year. Driving in heavy dust, off-road, or highly polluted environments may require earlier replacement; inspect the filter more often under those conditions.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eStandard service interval: replace every 18,000 miles under normal conditions.\u003c\/li\u003e\n  \u003cli\u003eInspect sooner for dusty or severe driving environments.\u003c\/li\u003e\n  \u003cli\u003eOne-year limited warranty for peace of mind.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat are the key construction and performance features?\u003c\/h3\u003e\n\u003cp\u003eThe KNA-2304 is built with durable materials chosen to provide a reliable service life while maintaining filtration efficiency. The overall design is focused on long-term protection and straightforward maintenance, combining rugged construction with filter media engineered to perform consistently.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eRugged construction for up to 18,000 miles of expected service life.\u003c\/li\u003e\n  \u003cli\u003ePremium filter media offering high-efficiency protection without significant airflow loss.\u003c\/li\u003e\n  \u003cli\u003eManufactured to meet or exceed OEM fit and performance specifications.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho is this for: This replacement air filter is intended for Subaru owners who want a reliable, longer-life disposable filter that installs like the original part. It suits daily drivers seeking extended service intervals, performance-minded owners who value consistent airflow, and anyone maintaining a Subaru model listed in the compatibility notes who prefers an OEM-fit aftermarket option.\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 the KNA-2304 a direct replacement for my Subaru air filter?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes — the KNA-2304 is a direct-fit replacement for many 2003–2021 Subaru H4\/H6 models listed by K\u0026amp;N and installs into the factory airbox.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: How long will the K\u0026amp;N Advantage Plus filter last?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Under normal highway driving the filter is rated for up to 18,000 miles; inspect earlier if you frequently drive in dusty or severe conditions.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"K\u0026N","offers":[{"title":"Default Title","offer_id":48086826549406,"sku":"B0DJPQV9HF","price":34.82,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0781\/2041\/9486\/files\/kandn-kna-2304-front-packaging.jpg?v=1785906873","url":"https:\/\/northtrailauto.ca\/products\/k-n-engine-air-filter-long-life-18-000-mile-replacement","provider":"North Trail Auto","version":"1.0","type":"link"}