Mercury - Oil Filter Adaptor O-Ring - 25-33756
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The Mercury Quicksilver Adaptor Sealing O-Ring 25-33756 is an OEM-style sealing ring used between the oil filter and filter valve/adaptor on select Mercury and MerCruiser engine applications. It helps keep pressurized engine oil sealed at the adaptor base and prevents leaks around the filter mounting area.
Key Features
- Genuine Mercury/Quicksilver sealing O-ring
- Part number: 25-33756
- Also referenced as 33756
- Oil filter adaptor / filter valve sealing ring
- Designed for engine oil sealing applications
- GTIN / UPC: 0745061136847
- Helps prevent oil seepage at the filter adaptor connection
Engine Compatibility
Used on select Mercury and MerCruiser engine applications where this O-ring is shown in the oil filter, filter valve, or adaptor parts diagram.
Serial Number Fitment Notice
Verify fitment by engine serial number and oil filter adaptor diagram before ordering. O-ring size and material can vary by engine block, filter adaptor style, and production range.
When This Part Needs Replacement
Replace this O-ring if oil is leaking around the filter adaptor, if the seal is flattened, cracked, swollen, hardened, cut, or removed during oil filter adaptor service.
Installation Notes
Clean the sealing groove and mating surfaces before installation. Lightly lubricate the O-ring with clean engine oil before assembly, and make sure it seats evenly without twisting or pinching.
Alternate/Superseded Part Numbers
Primary Mercury references: 25-33756 and 33756. Common aftermarket interchange: GLM Marine 42400.
Parts Desk Insight
Small oil-system O-rings can cause messy leaks when reused or pinched. Replacing the seal during adaptor service is a simple way to prevent repeat oil seepage.
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.