{"product_id":"mercury-4-stroke-marine-engine-oil-25w-40-quart-corrosion-protection-fc-w-catalyst-compatible","title":"MERCURY 4-Stroke Marine Engine Oil 25W-40 Quart — Corrosion Protection, FC-W Catalyst Compatible","description":"\u003cp\u003e\u003cstrong\u003eMERCURY 25W-40 4‑Stroke Marine Engine Oil (1 quart) is a purpose-built lubricant that protects and stabilizes four-stroke outboard, sterndrive and inboard engines in corrosive marine environments.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eMarine engines face salt, humidity, temperature swings and extended idle times that automotive oils don’t encounter. This Mercury 25W-40 formulation delivers thicker viscosity for hotter-running marine applications, a corrosion-targeted additive package, and industry certifications that meet or exceed marine OEM requirements. It’s supplied by Mercury Marine to their original equipment specifications, so it’s engineered for compatibility with Mercury, MerCruiser and many other four-stroke marine powerplants.\u003c\/p\u003e\n\n\u003ch3\u003eHow does this oil guard against corrosion on and off the water?\u003c\/h3\u003e\n\u003cp\u003eThe blend includes specialized rust and corrosion inhibitors that form a protective film on metal surfaces, reducing oxidation when the engine is wet or stored ashore. Those additives help preserve components during seasonal layups and frequent exposure to humid, salty air.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eCorrosion-inhibiting additives for external and internal protection\u003c\/li\u003e\n  \u003cli\u003eStable film formation that limits metal-to-metal contact\u003c\/li\u003e\n  \u003cli\u003eProvides protection during both operation and storage\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhy pick 25W‑40 for my four-stroke marine engine?\u003c\/h3\u003e\n\u003cp\u003e25W‑40 offers stronger viscosity at higher operating temperatures compared with lighter grades, making it well-suited for marine engines that run hot or under load. It maintains oil film thickness to protect bearings and cams while also resisting thinning from shearing and extended service intervals.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eHigher viscosity maintains oil film at elevated temperatures\u003c\/li\u003e\n  \u003cli\u003eGood shear stability for longer-lasting protection\u003c\/li\u003e\n  \u003cli\u003eRecommended where OEMs specify 25W‑40 for four-stroke marine use\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eIs this oil compatible with catalytic systems and industry standards?\u003c\/h3\u003e\n\u003cp\u003eYes—this Mercury product is certified FC‑W and marked as FC‑W Catalyst Compatible, so it meets recognized marine engine performance benchmarks and is formulated to be safe with compatible exhaust emission systems. It exceeds the marine industry requirements for four-stroke oils, helping preserve warranty compliance when the correct grade is used.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eFC‑W certification for marine four‑stroke performance\u003c\/li\u003e\n  \u003cli\u003eDesigned to be catalyst compatible where required\u003c\/li\u003e\n  \u003cli\u003eMeets or exceeds OEM warranty specifications\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow does this oil support wear protection and engine longevity?\u003c\/h3\u003e\n\u003cp\u003eThe formula combines robust base oils with anti-wear additives that reduce metal wear under load and during start-stop cycles. Consistent viscosity retention limits friction and bearing stress, contributing to extended engine life when the oil is changed at recommended intervals.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eAnti-wear chemistry to protect high-stress components\u003c\/li\u003e\n  \u003cli\u003eViscosity retention resists breakdown under heat and shear\u003c\/li\u003e\n  \u003cli\u003eManufactured to Mercury’s OEM performance and testing standards\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho is this for? Boaters, fleet operators and marine technicians who run four‑stroke outboard, sterndrive or inboard engines and need a quart-sized supply of a marine-grade 25W‑40 lubricant. It’s ideal for Mercury and MerCruiser owners looking for OEM-specified oil, anyone maintaining mixed-brand fleets that accept 25W‑40, and users who prioritize corrosion resistance, catalytic compatibility and proven wear protection. Use it where the engine manufacturer calls for 25W‑40 to maintain performance and warranty coverage.\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: Can I use this oil in outboards and sterndrives?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes. It’s formulated for four‑stroke outboard, sterndrive and inboard engines where 25W‑40 is specified.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Is this safe for engines with catalysts?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes. The formula is FC‑W Catalyst Compatible and meets industry standards for catalyst safety.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"MERCURY","offers":[{"title":"Default Title","offer_id":48084768587934,"sku":"B00K87NK70","price":34.98,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0781\/2041\/9486\/files\/mercury-25w40-quart-front-label.jpg?v=1785862452","url":"https:\/\/northtrailauto.ca\/products\/mercury-4-stroke-marine-engine-oil-25w-40-quart-corrosion-protection-fc-w-catalyst-compatible","provider":"North Trail Auto","version":"1.0","type":"link"}