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Inboard & I/O Engine Parts

Inboard Marine Engine Parts and Accessories

As the largest online dealer of inboard boat parts, Marine Parts Source will help you find the right engine parts you need for any project. We’re here to assist with seasonal maintenance, major repairs and more so you can get back on the water. Use our convenient categories to browse our collection — or if you know the part number you need, enter it into the search bar. From oil and fuel filters to spark plugs, exhaust manifolds, bell housings, starters and alternator belts, we supply boat owners from coast to coast.

You can always count on quality and knowledge when you shop with us. We’re an authorized dealer of the leading OEM and aftermarket performance inboard marine brands, including J&N Electric, Sierra, Arco Marine, Volvo Penta and Crusader. If you have a question, our sales associates have the technical expertise to answer it. Enjoy free ground shipping on qualifying orders so your vessel is ready for adventure.

Inboard & I/O Engine Parts

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    25W-40 4-Stroke Marine Engine Oil, 1 quart | Sierra 18-9400-2
    SIERRA-18-9400-2
    Qty In Stock: 185
    Brand: Sierra
    Sierra's Premium Blend engine oil is specially formulated to meet the needs of inboard & stern drive marine engines. Learn More
    MSRP: $14.99 $9.79
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  2. Large Image
    Full Synthetic 4-Stroke Oil SAE 30 - 5 qt. | Sierra 18-9410-4
    SIERRA-18-9410-4
    Qty In Stock: 78
    Brand: Sierra

    Fully synthetic straight 30-weight engine oil is formulated for Volvo inboard & stern drive marine engines.

    Learn More
    MSRP: $75.69 $49.25
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  3. Small Image
    25W-40 Catalyst Marine Engine Oil, 1 quart | Sierra 18-9400CAT-2
    SIERRA-18-9400CAT-2
    Qty In Stock: 131
    Brand: Sierra

    Premium Blend 25W-40 catalyst engine oil specially formulated to meet the needs of 4-stroke marine engines with catalyst emission systems

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    MSRP: $12.69 $10.81
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  4. Small Image
    25W-40 Catalyst Marine Engine Oil, 1 quart | Sierra 18-9440CAT-2
    SIERRA-18-9440CAT-2
    Qty In Stock: 133
    Brand: Sierra
    Synthetic blend 25W-40 engine oil is formulated for stern drive & inboard marine engines with catalyst emission systems. Learn More
    MSRP: $16.49 $9.99
    Add to Wishlist
  5. Sierra 18-9555-4 5W-30 FC-WCAT Semi-Synthetic Engine Oil
    5W-30 FC-WCAT Semi-Synthetic Engine Oil, 5 Quart | Sierra 18-9555-4
    SIERRA-18-9555-4
    Qty In Stock: 5

    5W-30 FC-WCAT Semi-Synthetic Engine Oil, 5 Quart

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    MSRP: $72.99 $44.90
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  6. Small Image
    25W-40 Marine Engine Oil, 1 quart | Sierra 18-9440-2P
    SIERRA-18-9440-2
    Qty In Stock: 112
    Brand: Sierra

    Synthetic blend 25W-40 engine oil formulated for stern drive & inboard marine engines

    Learn More
    MSRP: $17.89 $10.89
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  7. sierra-25W-40-4-stroke-engine-oil-5QT-18-9400-4
    4-Stroke Premium Blend Marine Engine Oil 25W-40 - 5 Quart | Sierra 18-9400-4
    SIERRA-18-9400-4
    Qty In Stock: 310
    Brand: Sierra
    Sierra's Premium Blend 25W-40 engine oil is specially formulated to meet the needs of inboard & stern drive marine engines. Learn More
    MSRP: $67.29 $46.90
    Add to Wishlist
  8. Sierra 18-9440CAT-4 25W-40 Synthetic Blend Catalyst Engine Oil - 5 qt.
    25W-40 Synthetic Blend Catalyst Engine Oil, 5 quart | Sierra 18-9440CAT-4
    SIERRA-18-9440CAT-4
    Qty In Stock: 137
    Brand: Sierra

    Synthetic blend 25W-40 engine oil is formulated for all 4-stroke applications including outboard, sterndrive, and inboard marine engines with catalyst emission systems. NMMA FC-W/API-SL certified and approved.

    Learn More
    MSRP: $74.39 $46.29
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  9. Small Image
    SAE 30 Full Synthetic Marine Engine Oil, 1 quart | Sierra 18-9410-2
    SIERRA-18-9410-2
    Qty In Stock: 38
    Brand: Sierra

    Fully synthetic straight 30 weight engine oil is formulated for inboard & stern drive marine engines

    Learn More
    MSRP: $16.39 $11.55
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  10. Small Image
    10W-30 Catalyst Marine Engine Oil, 1 quart | Sierra 18-9420CAT-2
    SIERRA-18-9420CAT-2
    Qty In Stock: 90
    Brand: Sierra
    Sierra's Premium Blend 10W-30 catalyst engine oil is specially formulated to meet the needs of 4-stroke outboards with catalyst emission systems. Learn More
    MSRP: $10.49 $8.65
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  11. Sierra 18-9690-3 4 Stroke Full Synthetic Oil 10W-30, 1 quart
    4 Stroke Full Synthetic Oil 10W-30, 1 Gallon | Sierra 18-9690-3
    SIERRA-18-9690-3
    Qty In Stock: 5
    Brand: Sierra

    Sierra's full synthetic engine oil optimizes engine life by reducing friction while providing wear protection in severe operating conditions. Used with outboard and sterndrive applications.

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    MSRP: $74.29 $55.57
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  12. Small Image
    25W-40 Synthetic Blend Oil, 5 quart | Sierra 18-9440-4
    SIERRA-18-9440-4
    Qty In Stock: 113
    Brand: Sierra

    Synthetic blend 25W-40 engine oil formulated for stern drive & inboard marine engines

    Learn More
    MSRP: $83.69 $53.54
    Add to Wishlist

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