Seachoice 50-21001 Full-Flow Oil Filter – 20 Micron | MerCruiser, Volvo Penta & OMC
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Seachoice 50-21001 Full-Flow Oil Filter – 20 Micron
Part Number: 50-21001 | SKU: 50-21001 | UPC: 719249210100
The Seachoice 50-21001 is a 20-micron full-flow spin-on marine oil filter for a wide range of MerCruiser, Mercury, OMC, Volvo Penta, Crusader, Chris-Craft, and Yamaha sterndrive applications. It crosses directly to Sierra 18-7824-2 and several OEM filter numbers. Built with high-efficiency cellulose filter media, an epoxy-coated canister, reinforced body construction, heavy-duty end-cap seals, and an anti-drain-back valve, it meets or exceeds original equipment filtration requirements.
Key Specifications
- Filtration: 20 micron
- Filter type: Full-flow spin-on
- Filter media: High-efficiency cellulose
- Anti-drain-back valve: Yes
- Canister: Epoxy-coated steel for corrosion resistance
- Body: Reinforced construction
- End-cap seals: Heavy-duty
- Manufactured in an ISO/TS 16949 certified facility
Compatible Applications
- MerCruiser sterndrive engines specifying filter 35-802885Q, 32716, or 866340K01
- Mercury sterndrive engines specifying filter 35-866340K01
- OMC sterndrive applications specifying filter 502902
- Volvo Penta sterndrive engines specifying filter 835440-9
- Crusader inboard engines specifying filter 201104
- Chris-Craft inboard engines specifying filter 16.81-08746
- Yamaha sterndrive applications specifying filter YSC-10231-20-0C
- Applications cross-referencing Sierra 18-7824-2
Fitment Note: Similar GM-based marine engines can use different short, long, or remote-mounted oil filter configurations. Always confirm your existing filter part number before ordering — matching an OEM cross-reference is more reliable than matching by appearance alone.
Service Interval
Replace at every engine oil change, following the engine manufacturer’s recommended service interval — typically every 100 hours of operation or once per season, whichever comes first.
Installation Notes
- Remove the old filter and confirm the old gasket has come away with it — a retained gasket will cause an oil leak
- Clean the filter mounting surface
- Lightly coat the new filter gasket with fresh engine oil before threading it on
- Tighten by hand plus ¾ turn, or per engine manufacturer specification — do not over-tighten
- Run the engine and inspect for leaks before returning to service
Cross-Reference Part Numbers
- Seachoice: 50-21001 / 21001
- Sierra: 18-7824-2
- MerCruiser: 35-802885Q, 32716
- MerCruiser / Mercury: 866340K01 / 35-866340K01
- OMC: 502902
- Volvo Penta: 835440-9
- Yamaha Sterndrive: YSC-10231-20-0C
- Chris-Craft: 16.81-08746
- Crusader: 201104
Related Products
- Sierra 18-7824-2 Marine Oil Filter – GM MerCruiser, Volvo Penta, OMC, Crusader & Indmar — OEM-equivalent this filter replaces
- Seachoice 50-21011 Full-Flow Oil Filter – 20 Micron — Mercury & Yamaha outboard application
- Seachoice 50-21018 Full-Flow Oil Filter – 20 Micron — alternate Seachoice marine filter
- Mallory 9-57825 Marine Oil Filter – GM MerCruiser, Crusader & OMC
Parts Desk Insights
Best Use Case: Routine oil and filter changes on MerCruiser and Mercury sterndrive engines, as well as OMC, Volvo Penta, Yamaha, Chris-Craft, and Crusader inboard applications. This is one of the most widely used filters for inboard and sterndrive boats — the Sierra 18-7824-2 cross-reference covers a broad swath of GM-based marine engine installations, making this a high-velocity maintenance stock item.
Common Issues: The most frequent ordering error is selecting the wrong GM marine filter style — similar-looking engines may use short-canister, long-canister, or remote-mount filter arrangements. Always confirm the existing filter’s part number first. Matching the Sierra 18-7824-2 or one of the listed OEM numbers is the fastest and most reliable way to confirm the correct filter for the application.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 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.