Sierra Premium Blend Heavy Duty Marine Engine Oil 15W-40 – 5 Qt
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
Sierra Premium Blend Heavy Duty Marine Engine Oil 15W-40 – 5 Qt
Engineered specifically for heavy-duty inboard marine engines, this 15W-40 premium blend oil is the right choice for cruisers, towboats, and high-hour diesel or gasoline inboard applications that demand more than a standard marine oil can deliver. Built on premium base stocks with an advanced additive package, it meets API CK-4 (diesel) and API SM (gasoline) service classifications — placing it at the top tier of marine lubrication performance.
The 5-quart jug provides enough volume for a complete oil change on most single inboard engines, with the convenience of a single container.
Key Benefits
- Meets API CK-4 diesel and API SM gasoline service classifications
- Suitable for all fuel sulfur levels — including high-sulfur diesel
- Premium blend formula delivers heavy-duty protection for high-load inboard applications
- Compatible with MerCruiser, Indmar, Pleasurecraft, Crusader, Volvo Penta, and Mastercraft engine specifications
- Not for use in gasoline engines equipped with catalytic converters — see FC-W Catalyst Compatible oils for those applications
Specifications
- Viscosity: 15W-40
- Type: Premium Blend
- Volume: 5 Quarts
- API Rating: CK-4 (diesel) / SM (gasoline)
- Application: Heavy-duty gasoline and diesel inboard marine engines
- Catalyst Compatible: No — not for use with catalytic converter-equipped engines
Related Products
- Sierra Heavy Duty 15W-40 Marine Engine Oil – 1 Qt
- Sierra 25W-40 FC-W Catalyst Compatible Marine Engine Oil – 5 Qt
- Sierra 25W-40 FC-W Catalyst Compatible Marine Engine Oil – 1 Qt
Parts Desk Insights
The 15W-40 heavy duty spec is the correct oil for older and high-displacement inboard diesel and gasoline engines — particularly trawlers, cruisers, and towboats running Indmar, Crusader, Pleasurecraft, or older MerCruiser and Volvo Penta inboard engines that call for a 15W-40. It is not suitable for engines with catalytic converters; if your engine has a catalyst system, use the Sierra 25W-40 FC-W Catalyst Compatible oil instead. The 5 Qt jug covers most single-engine inboard oil changes — check your engine manual for exact capacity. If you prefer to buy by the quart, the 1 Qt size is also available. Always confirm your engine’s oil specification before purchasing.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.