Seachoice 21003 Full-Flow Oil Filter – Honda, Yamaha & Nissan/Tohatsu | 50-21003

Seachoice 21003 Full-Flow Oil Filter

Part Number: 21003  |  SKU: 50-21003
Brand: Seachoice
Product Type: Full-Flow Spin-On Marine Oil Filter
Filtration Rating: 20 Micron
System: Engine Lubrication
UPC: 719249210033

Overview

The Seachoice 21003 is a 20-micron full-flow spin-on oil filter for compatible Honda, Yamaha, and Nissan/Tohatsu 4-stroke outboard engines. A direct replacement for Sierra 18-7911-1 and the corresponding OEM filter numbers, it features a high-efficiency cellulose filter element, anti-drain-back valve, epoxy-coated corrosion-resistant canister, reinforced body construction, and heavy-duty end-cap seals. Manufactured in an ISO/TS 16949 certified facility to meet or exceed OEM filtration performance.

Specifications

• Part Number: 21003 (SKU: 50-21003)
• Filter Type: Full-flow spin-on
• Filtration Rating: 20 micron
• Filter Media: High-efficiency cellulose
• Anti-Drain-Back Valve: Yes
• Canister: Epoxy-coated, reinforced heavy-wall steel
• End-Cap Seals: Heavy-duty
• Manufacturing Standard: ISO/TS 16949 certified facility
• Weight: Approx. 191 g (0.42 lb)
• System: Engine lubrication
• UPC: 719249210033

Compatible Applications

• Honda 4-stroke outboard engines where OEM filter 15400-PFB-007 is specified
• Yamaha 4-stroke outboard engines where OEM filter 5GH-13440-00-00 is specified
• Nissan / Tohatsu 4-stroke outboard engines where OEM filter 3R0-07615-0 is specified
• Any application where Sierra 18-7911-1 is the specified replacement filter

Fitment Notice: Honda, Yamaha, Nissan, and Tohatsu use multiple similar-looking spin-on filters across different engine families and model years. Always confirm by the OEM part number on the existing filter, not by physical size or appearance alone.

Cross-Reference Part Numbers

Seachoice 21003 replaces the following part numbers (verify by engine model and serial number):

• Sierra: 18-7911-1
• Honda: 15400-PFB-007
• Yamaha: 5GH-13440-00-00
• Nissan / Tohatsu: 3R0-07615-0

Service Interval

Replace at every engine oil change as specified by the outboard manufacturer — typically every 100 hours of operation or once per season, whichever comes first. Reusing an oil filter is not recommended even if it appears clean. Always follow your engine manufacturer’s maintenance schedule.

Installation

1. Run the engine briefly to warm the oil, then shut it down per the service procedure.
2. Remove the old filter and confirm the sealing gasket came away with it — do not leave the old gasket on the mounting surface.
3. Clean the filter mounting surface.
4. Lightly coat the new filter gasket with clean engine oil.
5. Spin the filter on by hand and tighten per the engine manufacturer’s specification — do not over-tighten.
6. Start the engine, check for leaks, and recheck oil level after shutdown.

Related Products

• Seachoice 21004 – Full-Flow Oil Filter (Mercury & MerCruiser)
• Sierra 18-7913 – 4-Cycle Outboard Oil Filter (Mercury & Honda)
• Sierra 18-7896 – 4-Cycle Outboard Oil Filter
• Sierra 18-7901 – 4-Cycle Outboard Oil Filter

Parts Desk Insights

Best Use Case: The Seachoice 21003 is a reliable value-priced filter for routine oil changes on Honda, Yamaha, and Nissan/Tohatsu 4-stroke outboards. Matching Sierra 18-7911-1 or one of the OEM numbers above is the quickest way to confirm this is the right filter for your engine.

Common Questions: These three brands use several different spin-on filters across their 4-stroke outboard lineups — don’t match by physical size alone. Always cross-reference by the OEM number on the filter you’re removing. If you’re unsure which filter your engine takes, contact us with your engine make, model year, and serial number and we’ll confirm the right part before you order.