AMSOIL Motor Oils
4-Stroke & Small Engine Oils
AMSOIL 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)

For use in 4-stroke gasoline fueled engines in marine applications. Offers unsurpassed wear protection, viscosity stability, low volatility and excellent rust protection. NMMA FC-W approved and "warranty certified". For use in 4-stroke outboard and marine inboard engines. Also excellent for personal watercraft.

Package sizes include:

1-Quart Bottle
1-Quart Bottles (case of 12)
55-Gallon Drum

AMSOIL Product Code: WCF

MSDS Sheet For AMSOIL WCF Product Data Sheet For AMSOIL WCF

Product Application
AMSOIL Formula 4-Stroke® Marine Synthetic 10W-40 Motor Oil (WCF) is recommended for gasoline fueled four-stroke outboard, inboard, inboard/outboard (I/O) and personal watercraft motors. AMSOIL WCF motor oil is recommended for the following applications whenever an SAE 10W-40, 15W-40, 25W-40 or straight SAE 40 oil is called for:

Four-stroke outboard motors: Honda®, Mercury®, Yamaha®, Johnson®/Evinrude®, Bombardier/BRP®, Suzuki®, Nissan®, Tohatsu®, OMC®, Volvo Penta®, Mercruiser®, Chevrolet®, Ford®

Inboard and I/O: Mercruiser®, Volvo Penta®, OMC®, Chrysler® Marine, Crusader®, Marine Power®, Chevrolet®, Ford®

Personal Watercraft: Honda®, Yamaha®, Bombardier/BRP® (Sea-Doo®), Polaris®

Note: AMSOIL Formula 4-Stroke® Marine Synthetic 10W-40 is recommended for use in place of 25W-40 as specified by Mercury®.

NMMA FC-W Catalyst Compatible • API SM

Product Description
AMSOIL Formula 4-Stroke® Marine Synthetic Motor Oil is a premium-quality synthetic formulation engineered for the harsh operating conditions of marine environments. It withstands the intense mechanical action of continuous, high-rpm operation to deliver superior viscosity protection. Formula 4-Stroke Marine Synthetic Motor Oil is specially fortified with a heavy treatment of advanced additives that protect

4-Stroke Outboard Motor Warranty Certified
Formula 4-Stroke® Marine Synthetic Motor Oil is certified by the National Marine Manufacturers Association (NMMA) for use in four-stroke outboard motors. This high quality oil demonstrates outstanding performance, exceeding the NMMA “FC-W” (Four Cycle-Water) specification requirements. Formula 4-Stroke® Marine Synthetic Motor Oil fulfills the warranty requirements of four-stroke outboard motor manufacturers.

• NMMA Registration #FB-30010B 10W-40

Superior Protection Against Engine Wear
Marine engines operate under high loads and RPMs for extended periods of time, causing traditional automotive oils to break down and lose viscosity. To ensure good protection, the NMMA set minimum shear stability requirements for FC-W. AMSOIL Formula 4-Stroke® Marine Synthetic Motor Oil greatly exceeds the FC-W shear stability requirements, outperforming competitive oils to deliver a superior lubricating film. Formula 4-Stroke® Synthetic Oil also contains robust anti-wear additives that further reduce wear in metal-to-metal contact regions (see Four-Ball Wear Test graph).

4 ball Test

HTHS Viscosity
While automobile engines normally operate at around 2,500 rpm, outboard motors can run twice as fast, requiring greater levels of wear protection and better bearing durability than automobiles. In addition, prolonged idling and low operating temperatures contribute to fuel dilution, further thinning the oil. To ensure adequate protection for their engines, marine engine manufacturers set minimum high temperature/high shear (HTHS) viscosity limits. AMSOIL Formula 4-Stroke® Marine Synthetic Motor Oils are shear stable and formulated with sophisticated oil additive chemistry, exceeding the HTHS requirements of both the API and NMMA FC-W (see graph).

HTHS Viscosity

Excellent Anti-Rust Performance
Marine engines are prone to rust, leading to uncontrolled wear and premature engine failure. However, good rust protection is not natural to engine oil. It comes only by design. Formula 4-Stroke® Marine Synthetic Motor Oil is fortified with a special anti-rust agent, even more than required to pass stringent NMMA FC-W anti-rust testing.

Service Life
Four-stroke outboard motors and personal watercraft applications: Due to potential fuel dilution or water contamination, change oil at the engine or watercraft manufacturer recommended interval.

Inboard and I/O applications: Change oil at two times the engine manufacturer recommended interval or one year, whichever comes first.

AMSOIL Formula 4-Stroke® Marine Synthetic Motor Oil is compatible with conventional and synthetic motor oils. Mixing AMSOIL motor oils with other oils will, however, shorten the oil life expectancy and reduce the performance benefits. AMSOIL does not support extended drain intervals where oils have been mixed.

Aftermarket oil additives are not recommended for use with AMSOIL motor oils.

This product is not expected to cause health concerns when used for the intended application and according to the recommendations in the Material Safety Data Sheet (MSDS).

Click here to view the MSDS Data Sheet for AMSOIL WCF.

Keep out of the reach of children. Don't pollute. Return used oil to collection centers.


SAE 10W-40

Kinematic Viscosity @ 100°C, cSt (ASTM D445) 14.1
Kinematic Viscosity @ 40°C, cSt (ASTM D445) 93.3
Viscosity Index (ASTM D2270) 155
Pour Point °C (°F) (ASTM D97) -38 (-36)
Flash Point °C (°F) (ASTM D92) 240 (464)
High-Temperature/High-Shear Viscosity (ASTM D5481)4.2
Four Ball Wear Test (ASTM D4172 @ 40 kgf, 150°C, 1800 rpm, 1 hour, Scar in mm) 0.40
Noack Volatility, % weight loss (g/100g) (ASTM D5800) 7.5
Total Base Number (ASTM D2896) 7.9
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