AMSOIL Oil Filter ASF-25
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The AMSOIL ASF-25 is a legacy full-flow spin-on oil filter associated with older GM gasoline-engine and GM-based marine applications. It removes abrasive contaminants from circulating engine oil while maintaining the flow required to protect bearings, journals and other lubricated components.
ASF-25 belongs to the common short GM filter family and is cross-referenced with AMSOIL EAO25, WIX 51069, Baldwin B27 and FRAM PH30. The comparable WIX 51069 uses a 13/16"-16 mounting thread and measures approximately 3.82 inches high by 3.66 inches in diameter.
Key Features
- Legacy AMSOIL full-flow engine-oil filter
- Short-format GM filter configuration
- Thread size: 13/16"-16
- Approximate filter-family height: 3.82 inches / 97 mm
- Approximate outside diameter: 3.66 inches / 93 mm
- Commonly associated nominal filtration rating: 21 microns
- Associated full-flow capacity: approximately 9–11 GPM
- Suitable for compatible gasoline and marine-engine lubrication systems
- Legacy AMSOIL part number: ASF-25
- Later AMSOIL cross-reference: EAO25
Engine Compatibility
Cross-reference data associates the ASF-25 filter family with select older GM-based marine engines and related equipment, including applications from:
- MerCruiser
- OMC
- Crusader
- Pleasurecraft Marine / PCM
- Marine Power
- Volvo Penta
- Chris-Craft
- Older GM passenger-car, truck and industrial engines
The corresponding current Quicksilver marine filter family is used on many MerCruiser sterndrive and inboard engines, except certain V6 engines with the oil filter mounted directly on the engine block. Exact compatibility depends on the engine year, marinizer and installed filter location.
Serial Number Fitment Notice
Confirm the engine model, serial number, filter location and number printed on the existing filter before ordering.
Many GM filters share the same 13/16"-16 thread and similar outside dimensions. A filter that screws onto the mounting pad may still have a different gasket, valve arrangement, flow capacity or body length. V6 marine engines are particularly important to verify because remote-mounted and block-mounted filter systems may use different filters.
When This Part Needs Replacement
Replace the oil filter whenever the engine oil is changed or at the interval specified by the engine manufacturer.
Earlier replacement may be appropriate following:
- Extended trolling or low-speed operation
- Heavy-load or high-temperature use
- Fuel, coolant, water or debris contamination
- Long periods of seasonal storage
- Internal engine repairs
- Abnormal oil-pressure conditions
ASF-25 is a discontinued legacy number. Do not install an old-stock filter if its canister is rusted or dented, its gasket is hardened or cracked, or its storage history is uncertain.
Installation Notes
Remove the existing filter and confirm that its sealing gasket has not remained attached to the filter head. Clean the mounting surface and compare the new filter's thread, gasket diameter and body length with the removed filter.
Lightly coat the replacement gasket with clean engine oil and install the filter by hand according to the engine manufacturer's tightening instructions. Do not overtighten.
After installation:
- Refill the engine with the specified oil.
- Start the engine and confirm normal oil pressure.
- Inspect the filter body and gasket for leakage.
- Shut the engine down and allow the oil to settle.
- Recheck and correct the engine-oil level.
Alternate/Superseded Part Numbers
Commonly associated replacement and cross-reference numbers include:
- AMSOIL ASF25
- AMSOIL ASF-25
- AMSOIL EAO25
- WIX 51069
- WIX 51046
- NAPA Gold 1069
- NAPA Gold 1046
- Baldwin B27
- Donaldson P550025
- Fleetguard LF651
- FRAM PH30
- ACDelco PF25
- Sierra 18-7824
- MerCruiser 32716
- MerCruiser 32717
- MerCruiser 35-802885Q
- MerCruiser 866340Q02
- MerCruiser 54111
- OMC 173232
- OMC 502902
- Crusader 201104
- Pleasurecraft R077002
- Volvo Penta 835440
- Volvo Penta 3850559
Cross-reference numbers are comparison aids only. Confirm the original filter number and complete engine application before substituting brands.
Parts Desk Insight
ASF-25 is part of the familiar short GM filter family, but the thread alone does not confirm fitment. On marine engines, checking whether the filter is mounted directly on the block or on a remote filter head usually prevents the most common ordering mistake.
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.