Sierra Premium Blend Heavy Duty Marine Engine Oil 15W-40 – 1 Qt
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Sierra Premium Blend Heavy Duty Marine Engine Oil 15W-40 – 1 Qt
Engineered for heavy-duty inboard marine engines, this 15W-40 premium blend oil is built for cruisers, towboats, and high-hour diesel or gasoline inboard applications that demand more than a standard marine oil can deliver. It meets API CK-4 (diesel) and API SM (gasoline) service classifications and is suitable for all fuel sulfur levels — making it a versatile choice for both diesel and gasoline inboard engines in demanding marine environments.
The 1-quart size is ideal for topping up between oil changes, keeping a spare aboard, or purchasing the exact quantity needed for a partial service.
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: 1 Quart
- 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 – 5 Qt
- Sierra 25W-40 FC-W Catalyst Compatible Marine Engine Oil – 1 Qt
- Sierra 25W-40 FC-W Catalyst Compatible Marine Engine Oil – 5 Qt
Parts Desk Insights
The 1-quart size is best for topping up oil between scheduled changes or keeping a spare aboard — most inboard engines require 4–8 quarts for a full oil change, so the 5-quart jug is the more practical choice for a complete service. The 15W-40 heavy duty spec is correct for older and high-displacement inboard diesel and gasoline engines — trawlers, cruisers, and towboats running Indmar, Crusader, Pleasurecraft, or older MerCruiser and Volvo Penta inboard engines that specify 15W-40. It is not suitable for engines with catalytic converters; for those, use the Sierra 25W-40 FC-W Catalyst Compatible oil instead. Always confirm your engine’s oil specification in the owner’s manual 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.