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AMSOIL Marine Dual Remote Bypass Filtration System

The Marine Dual Remote Filtration System was created to address the specific severe operating environment of marine engines in both salt and fresh water. These torturous conditions place tremendous stress on engines and engine oils. AMSOIL EaBP Bypass Filters have an efficiency of 98.7 percent (Beta 75) at TWO microns and 60 percent at one micron.Since clean engine oil is critical for ensuring proper operation and protection of expensive marine equipment, this system is recommended for marine gas and diesel engines with sump capacity up to 21 quarts depending upon size of EaBP Bypass Filter element used.

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SKU: BMK18 Category:

Marine Bypass System

Offers easily accessible remote mounting capability for a full-flow spin-on oil filter and a spin-on by-pass oil filter for marine applications. Must purchase separately the spin on adapter that matches the engine’s filter thread.

PDF5 Warranty

Product Description
The Marine Bypass System (BMK18) offers easily accessible remote mounting capability for a full-flow spin-on oil filter and a spin-on by-pass oil filter. This unique combination of both full-flow and by-pass filtration on a single mounting manifold is the only system of this kind designed specifically for marine applications.

Improved Performance

bmk18_02_200pxThe effects of marine engines running predominantly at or near full throttle after extended periods of non-activity include high operating temperatures and increased potential for wear on engine components. Dual remote filtration is a highly efficient filtering process capable of removing the vast majority of particles in the 5-20 micron range; those that cause the most wear. Dual remote filtration also has the ability to effectively remove particles down to one micron in size. The AMSOIL Marine Bypass System (BMK18) offers a clear advantage by providing better oil filtration, increased oil capacity and longer oil and filter life.

Reduces Heat
The BMK18 requires a one- to two-quart oil volume increase, offering increased oil cooling capabilities. The additional hoses, fittings, filters and aluminum mount assemblies also allow the engine oil to dissipate heat more efficiently as it passes through the filtration system, extending the service life of both the engine and the engine oil.

Outstanding Durability

bmk18_03_200pxThe Marine Bypass System is designed to be used in harsh marine environments. The hose fittings are coated with a 3 ml layer of Alumiplate™ and 1 ml of zinc and yellow chromate. This Alumiplate coating is 10 times more corrosion resistant than standard zinc and yellow chromate plated fittings. While standard hydraulic fittings typically survive 96 hours in the grueling ASTM B-117 Salt Spray Test, the Alumiplate-coated AMSOIL Marine By-Pass System fittings lasted over 1,000 hours. In addition, the fasteners and mounting bracket are stainless steel and the hoses are U.S. Coast Guard approved.

Fewer Oil Changes
Depending on the boat owner’s hours of use, the improved filtration of the Marine Dual Remote System, along with the use of AMSOIL synthetic lubricants, could completely eliminate oil and filter changes during a typical boating season. With marine engines located in a relatively confined and remote space within the watercraft, ease of filter access and reduced oil spillage are also significant benefits of the BMK18.

A large number of marine diesel engines have by-pass oil filtration systems installed by the engine manufacturer. Until now, however, this technology has not been available to smaller pleasure boats and light commercial marine applications. The AMSOIL Marine Bypass System was specifically designed for recreational and commercial marine applications that use inboard or inboard/outboard stern drive engines.

The BMK18 is packaged in kit form, which includes the Dual filter mount, mounting hardware, hoses, hose fittings, component parts and installation instructions. In addition, adapter kits of four different sizes enable the BMK18 to be installed on a wide variety of recreational and light commercial marine gasoline-fueled engines, including those manufactured by Chris Craft, Chrysler, Crusader, Evinrude, Johnson, Gray Marine, Mercruiser, OMC, Pleasurecraft, Universal, Volvo Penta and Westerbeke.

The BMK18 kit offers a new heavy-duty, machined aluminum adapter and retaining nut that fits on the existing oil filter mount. Each adapter kit is application specific and must be ordered separately. Consult the Marine Dual Remote Application Guide (G2051) or for specific applications. Adapter kits are available for the most popular filter thread sizes.

The AMSOIL Marine Bypass System represents the cutting edge of filtration technology, another example of the AMSOIL commitment to providing quality innovations that benefit consumers everywhere.



Oil Capacity
1 to 2 quart increase
Corrosion resistant
External oil filter changes
Remove moisture and condensation
Ease/convenience of maintenance
Contaminant removal
Down to 1 micron


BP239 Marine Bypass System Installation Instructions (PDF – 1.80MB)


If your equipment uses
this AMSOIL Filter
This is the thread used on that equipment
EAO11M22 x 1.5
EAO153/4 – 16 UNF
EAO17M22 x 1.5
EAO23M18 x 1.5
EAO2413/16 – 16UNS
EAO263/4 – 16 UNF
EAO343/4 – 16 UNS
EAO383/4 – 16 UNS
EAO423/4 – 16UNF
EAO5213/16 – 16UNS
EAO5913/16 – 16UNS
EAO6413/16 – 16UNS
EAO801 – 16UNF
EAO981 – 16UNF
EAO991 1/2 – 16UN
EA15K093/4 – 16UNS
EA15K12M20 x 1.5
EA15K13M20 x 1.5
EA15K20M20 x 1.5
EA15K29M18 x 1.5
EA15K3213/16 – 16UNS
EA15K50M22 x 1.5
EA15K513/4 – 16 UNS
3/4″ – 16BK295
13/16″ – 16BK296
18mm x 1.5mmBK297
20mm x 1.5mmBK298
22mm x 1.5mmBK299
When ordering the BMK23:
– Spin-on Adapter BP402M is designed for 2008-Present Chevrolet 1500 & 2500 gas engines.
1″ – 16 (Cummins)BK300
1-1/2″ – 16 (Power Stroke 7.2 L)BK301
13/16″ – 16 (Duramax 6.6 L)BK302

BMK18 Packaging Information


CodePart NumberUnit of MeasureProduct
BMK18-EABMK18EachMarine Bypass System