{"product_id":"sierra-5w-30-fc-w-catalyst-marine-oil-5-qt-18-9555cat-4","title":"Sierra 5W-30 FC-W Catalyst Marine Oil, 5 Qt 18-9555CAT-4","description":"\u003cp class=\"nvn-hero\"\u003eSierra's 5W-30 Semi-Synthetic Catalyst Marine Engine Oil is built for modern four-stroke gasoline engines that need a catalyst-safe fluid. This 5-quart bottle carries the NMMA FC-W Catalyst rating and meets or exceeds API SM, delivering fast cold-start flow, strong film strength under load, and the corrosion protection a marine engine needs.\u003c\/p\u003e\n\n\u003cdiv class=\"nvn-description\"\u003e\n\u003cp\u003eSierra's 5W-30 Semi-Synthetic Catalyst Marine Engine Oil is built for one job. Keeping a modern four-stroke marine gasoline engine running clean through a hard season on the water. This is the 5-quart bottle, sold single. It carries the NMMA FC-W Catalyst rating and meets or exceeds API SM, so it's formulated for today's engines and the emissions gear that rides along with them.\u003c\/p\u003e\n\u003cp\u003eThe Catalyst part matters more than a lot of boaters realize. Newer four-stroke engines run catalytic converters to meet emissions rules, and the wrong oil additive package can foul that catalyst over time. FC-W Catalyst oils are blended with a controlled additive chemistry that looks after the converter while still delivering the wear and corrosion protection a marine engine demands. If your engine calls for a catalyst-compatible oil, this is the box you want to check. Run a standard automotive oil in one of these engines and you're gambling with an expensive part.\u003c\/p\u003e\n\u003cp\u003eNow the viscosity. 5W-30 is a wide spread, and that's the point. The 5W side flows fast on a cold morning start, so oil reaches the top end before the bearings ever get thirsty. The 30 weight holds its film strength once everything warms up and the engine's pulling hard. Cold starts are where a lot of engine wear actually happens, so that fast initial flow is doing real work every time you turn the key. It's a semi-synthetic, which is a synthetic blend. You get a big chunk of the cold-flow and oxidation resistance of a full synthetic without paying the full-synthetic price. For most weekend and mid-use boats, that's the sweet spot.\u003c\/p\u003e\n\u003cp\u003eThis oil runs in four-stroke marine gasoline engines. Think inboards, sterndrives, and four-stroke outboards that spec a 5W-30 FC-W Catalyst fluid. And here's why marine-specific oil matters. A boat engine lives a harder life than a car engine ever will. Sustained high RPM, wide-open throttle runs, salt and humidity working on everything, then long stretches sitting idle at the dock between trips. Marine oil like this is built with extra corrosion inhibitors for exactly that pattern, so the internals stay protected even when the boat hasn't moved in three weeks.\u003c\/p\u003e\n\u003cp\u003eChange intervals come down to your engine builder's recommendation, so check the manual first. That said, if you're running ethanol-blended pump fuel all season, it's worth shortening the interval. Plenty of owners drop to 50 or 75 hours on E10 instead of stretching to 100. Marine oil breaks down faster than most people expect when fuel and moisture sneak into the crankcase, so staying ahead of the schedule pays off. Change the oil filter every single time you change the oil, and stick with a quality marine spin-on filter. Cheap aftermarket filters can cause bypass-valve headaches, and that's the last thing you want between oil changes.\u003c\/p\u003e\n\u003cp\u003eA quick word on what this oil isn't for. It's a gasoline four-stroke oil, full stop. It's not meant for high-output turbo diesels that need a heavier viscosity, and it's not a two-stroke oil, so don't reach for it if your engine takes a TC-W3 fluid. When in doubt, your owner's manual spells out the exact grade and spec. If it lists 5W-30 and FC-W Catalyst, you're holding the right bottle.\u003c\/p\u003e\n\u003cp\u003eSierra has been supplying engine parts and fluids to boat builders and marine OEMs for decades, and their oils are formulated to meet or exceed the original spec they replace. One 5-quart bottle covers a typical single oil change on many small to mid-size four-stroke engines. We'd keep a spare aboard or on the shelf so an oil change never gets held up waiting on a parts run. It's one of the cheapest things you'll ever do to keep an engine alive. Simple insurance for a part of the boat you really don't want to neglect.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul class=\"nvn-features\"\u003e\n  \u003cli\u003eSAE 5W-30 viscosity grade: fast cold-start flow with strong film strength under sustained load.\u003c\/li\u003e\n  \u003cli\u003eNMMA FC-W Catalyst certified: safe for catalyst-equipped four-stroke marine engines and their emissions systems.\u003c\/li\u003e\n  \u003cli\u003eMeets or exceeds API SM: covers the service requirements of modern four-stroke gasoline engines.\u003c\/li\u003e\n  \u003cli\u003eSemi-synthetic (synthetic blend) formula: much of a full synthetic's cold-flow and oxidation resistance at a friendlier price.\u003c\/li\u003e\n  \u003cli\u003eMarine-specific additive package: extra protection against corrosion, wear, and deposits in a wet, high-load environment.\u003c\/li\u003e\n  \u003cli\u003e5-quart single bottle: covers a typical single oil change on many small to mid-size four-stroke engines.\u003c\/li\u003e\n  \u003cli\u003eFormulated for four-stroke gasoline inboards, sterndrives, and outboards that spec a 5W-30 FC-W Catalyst oil.\u003c\/li\u003e\n  \u003cli\u003eSierra quality: engineered to meet or exceed the original equipment fluid it replaces.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cdiv class=\"nvn-trust\"\u003e\n  \u003ch2\u003eWhy Buy from NVN Marine\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eAuthorized Sierra Marine reseller, full manufacturer warranty\u003c\/li\u003e\n    \u003cli\u003eNMEA member and ABYC certified, advice from real boat techs\u003c\/li\u003e\n    \u003cli\u003eSame-day shipping before 3 PM ET on in-stock items\u003c\/li\u003e\n    \u003cli\u003eNY headquarters and Fort Lauderdale flagship retail store\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cdiv class=\"nvn-faq\"\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat does the FC-W Catalyst rating mean?\u003c\/summary\u003e\n    \u003cp\u003eIt's the NMMA's marine oil standard for engines equipped with a catalytic converter. FC-W Catalyst oils use a controlled additive package that protects the catalyst while still guarding against wear, deposits, and corrosion. If your four-stroke engine has a catalyst, it needs a catalyst-compatible oil like this one.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat engines is this oil made for?\u003c\/summary\u003e\n    \u003cp\u003eFour-stroke marine gasoline engines that call for a 5W-30 FC-W Catalyst fluid, including inboards, sterndrives, and four-stroke outboards. Check your owner's manual for the exact grade your engine specifies.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow much oil is in the bottle?\u003c\/summary\u003e\n    \u003cp\u003eFive quarts in a single bottle. That covers a typical single oil change on many small to mid-size four-stroke engines. Larger engines may need more than one bottle.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eIs this a full synthetic or a blend?\u003c\/summary\u003e\n    \u003cp\u003eIt's a semi-synthetic, also called a synthetic blend. You get much of the cold-flow and oxidation resistance of a full synthetic at a friendlier price.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat's the difference between FC-W and FC-W Catalyst oil?\u003c\/summary\u003e\n    \u003cp\u003eBoth are NMMA four-stroke marine oil ratings. The Catalyst version uses an additive chemistry that's safe for engines fitted with a catalytic converter, so it won't foul that emissions hardware over time.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eDoes it meet API SM?\u003c\/summary\u003e\n    \u003cp\u003eYes. This oil meets or exceeds the API SM service category for four-stroke gasoline engines, on top of its marine FC-W Catalyst rating.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow often should I change it?\u003c\/summary\u003e\n    \u003cp\u003eFollow your engine builder's recommended interval. If you run ethanol-blended fuel, many owners shorten the interval to around 50 to 75 hours rather than stretching it. Change the oil filter every time you change the oil.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow does 5W-30 perform in cold weather?\u003c\/summary\u003e\n    \u003cp\u003eThe 5W rating means it flows quickly at cold start, so oil reaches the top of the engine fast on a cold morning. The 30 weight then holds its film strength once the engine warms up and works under load.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eCan I use this in a two-stroke or diesel engine?\u003c\/summary\u003e\n    \u003cp\u003eNo. This is a four-stroke gasoline oil. It's not a two-stroke TC-W3 oil, and it's not formulated for diesels that need a heavier viscosity. Always match the oil to the spec in your engine manual.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003ctable class=\"nvn-specs\"\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003cth\u003eTitle\u003c\/th\u003e\n\u003ctd\u003eSierra 18-9555CAT-4 5W-30 FC-W Catalyst Semi-Synthetic Marine Engine Oil, 5 Quart\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003ctd\u003eSierra Marine\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eManufacturer Part Number\u003c\/th\u003e\n\u003ctd\u003e18-9555CAT-4\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eUPC\u003c\/th\u003e\n\u003ctd\u003e808282390112\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eViscosity Grade\u003c\/th\u003e\n\u003ctd\u003eSAE 5W-30\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eOil Type\u003c\/th\u003e\n\u003ctd\u003eSemi-Synthetic (Synthetic Blend)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eCatalyst Compatible\u003c\/th\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eMarine Certification\u003c\/th\u003e\n\u003ctd\u003eNMMA FC-W \/ FC-W Catalyst\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eAPI Service Category\u003c\/th\u003e\n\u003ctd\u003eAPI SM\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eEngine Type\u003c\/th\u003e\n\u003ctd\u003eFour-Stroke Gasoline\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eApplication\u003c\/th\u003e\n\u003ctd\u003eInboard, Sterndrive, Outboard\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eVolume\u003c\/th\u003e\n\u003ctd\u003e5 Quarts\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eContainer\u003c\/th\u003e\n\u003ctd\u003eSingle Bottle\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eKeystone Part Number\u003c\/th\u003e\n\u003ctd\u003eS5M189555CAT4\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n    \"@context\": \"https:\/\/schema.org\",\n    \"@type\": \"FAQPage\",\n    \"mainEntity\": [\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What does the FC-W Catalyst rating mean?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"It's the NMMA's marine oil standard for engines equipped with a catalytic converter. FC-W Catalyst oils use a controlled additive package that protects the catalyst while still guarding against wear, deposits, and corrosion. If your four-stroke engine has a catalyst, it needs a catalyst-compatible oil like this one.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What engines is this oil made for?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Four-stroke marine gasoline engines that call for a 5W-30 FC-W Catalyst fluid, including inboards, sterndrives, and four-stroke outboards. Check your owner's manual for the exact grade your engine specifies.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"How much oil is in the bottle?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Five quarts in a single bottle. That covers a typical single oil change on many small to mid-size four-stroke engines. Larger engines may need more than one bottle.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Is this a full synthetic or a blend?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"It's a semi-synthetic, also called a synthetic blend. You get much of the cold-flow and oxidation resistance of a full synthetic at a friendlier price.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What's the difference between FC-W and FC-W Catalyst oil?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Both are NMMA four-stroke marine oil ratings. The Catalyst version uses an additive chemistry that's safe for engines fitted with a catalytic converter, so it won't foul that emissions hardware over time.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Does it meet API SM?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Yes. This oil meets or exceeds the API SM service category for four-stroke gasoline engines, on top of its marine FC-W Catalyst rating.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"How often should I change it?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Follow your engine builder's recommended interval. If you run ethanol-blended fuel, many owners shorten the interval to around 50 to 75 hours rather than stretching it. Change the oil filter every time you change the oil.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"How does 5W-30 perform in cold weather?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"The 5W rating means it flows quickly at cold start, so oil reaches the top of the engine fast on a cold morning. The 30 weight then holds its film strength once the engine warms up and works under load.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Can I use this in a two-stroke or diesel engine?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"No. This is a four-stroke gasoline oil. It's not a two-stroke TC-W3 oil, and it's not formulated for diesels that need a heavier viscosity. Always match the oil to the spec in your engine manual.\"\n            }\n        }\n    ]\n}\n\u003c\/script\u003e\n","brand":"Sierra Marine","offers":[{"title":"Default Title","offer_id":45072257286237,"sku":"2009184","price":49.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0299\/7266\/0317\/files\/ImageServerAPI_ffd03946-6008-4835-a8cd-4c01690fae05.jpg?v=1789733694","url":"https:\/\/nvnmarine.com\/products\/sierra-5w-30-fc-w-catalyst-marine-oil-5-qt-18-9555cat-4","provider":"NVN Marine","version":"1.0","type":"link"}