Mallory 9-57800 Marine Oil Filter – Mercury, Mariner & Honda Outboards
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Mallory 9-57800 Marine Oil Filter – Mercury, Mariner & Honda Outboards
The Mallory Marine 9-57800 is a compact, full-flow spin-on oil filter for select Mercury, Mariner, and Honda four-stroke outboards. It removes harmful contaminants from circulating engine oil while maintaining the lubrication flow needed to protect bearings, journals, and other internal engine components.
This marine filter specification uses a 20 mm × 1.5 mounting thread and includes an anti-drainback valve to help retain oil during shutdown for faster lubrication at startup. Current equivalent marine filters feature corrosion-resistant canisters and high-efficiency filtration media suited to the marine environment.
Key Features
- Full-flow spin-on engine oil filter
- Designed for select four-stroke outboard applications
- Thread specification: 20 mm × 1.5
- Anti-drainback valve helps reduce dry starts
- Marine-grade corrosion-resistant replacement options
- Heavy-wall steel replacement filter construction
- High-efficiency filtration media
- Current Quicksilver replacement uses a 20-micron filter element
- Legacy Mallory part number: 9-57800
Engine Compatibility
Common applications include select Mercury and Mariner four-stroke outboards:
- 8 and 9.9 hp, 323 cc models
- 15 and 20 hp carbureted models
- 25 and 30 hp EFI models from model year 2006 onward
- Select 25/30 hp EFI engines from serial number 0T801000 onward using the 492/498 cc cylinder block
The same filter specification is also associated with select Honda four-stroke outboards using Honda filter numbers including 15400-PFB-004, 15400-PFB-014, 15400-PJ7-005, 15400-PJ7-015, 15400-PM3-004, 15400-PM3-405, and 15400-ZZ3-003.
Fitment Notice
Confirm the outboard model, model year, serial number, and number printed on the existing filter before ordering. Mercury and Mariner engines with the same advertised horsepower may use different oil filters depending on displacement, production range, and engine family. Do not select this filter by its 20 mm × 1.5 thread alone — the body size, sealing-gasket dimensions, anti-drainback valve, and internal filtration specifications must also match the engine.
When to Replace
Replace the oil filter at the interval specified in the outboard owner’s manual. Mercury recommends replacement at least once each boating season and before winter storage, with shorter intervals where required by engine hours or operating conditions. Earlier replacement may be appropriate following extended trolling or low-speed operation, frequent short operating cycles, heavy-load or high-temperature use, fuel, water or debris contamination, internal engine repairs, abnormal oil-pressure conditions, or visible corrosion, denting, or leakage.
Installation Notes
Remove the old filter and confirm its sealing gasket has not remained on the engine’s filter mount. Clean the sealing surface and lightly lubricate the replacement filter gasket with clean engine oil. Install by hand to the manufacturer’s tightening specification — do not overtighten. After installation: refill with the specified oil, start the engine and allow oil pressure to build, inspect for leakage, shut down and allow oil to settle, then recheck and correct the oil level.
Cross-Reference Numbers
- Mallory 9-57800
- Sierra 18-7913
- EMP 35-57800
- Quicksilver 8M0154778 / 8M0162832 / 35-822626Q03 / 35-822626Q1
- Mercury 8M0162831 / 35-822626 / 35-822626A1 / 35-822626K03 / 35-822626T1 / 35-851847A02
- Honda 15400-PFB-004 / 15400-PFB-014 / 15400-PJ7-005 / 15400-PJ7-015 / 15400-PM3-004 / 15400-PM3-405 / 15400-ZZ3-003
Cross-reference numbers are comparison aids. Confirm the exact outboard model and serial-number range before substituting filters.
Other Marine Oil Filters
- Mallory 9-57825 – GM MerCruiser, Crusader & OMC
- WIX Oil Filter 51083 – Mercury & Mariner Outboards
- WIX Oil Filter 51365 – Honda Marine, Tohatsu & Yanmar
- WIX Oil Filter 51061 – GM Tall Marine
Parts Desk Insights
This filter is used across several small four-stroke outboard families, but horsepower alone is not enough to confirm fitment. Matching the old filter number and engine serial number is the safest way to avoid selecting a similar-looking filter intended for a different engine block. The Honda cross-references are particularly useful — if you’re fitting a Honda outboard and the 9-57800 is unavailable, the WIX 51365 covers many of the same Honda applications and is worth cross-checking against your engine serial number.
Shipping: Ships same or next day for fast Canada-wide shipping. ⚓
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.