Engine performance and reliability are key to a successful day fishing or boating. High-rpm operation and constant exposure to water, however, invite engine wear and formation of rust and corrosion, reducing engine performance and life. AMSOIL 25W-40 Synthetic Blend Marine Engine Oil guards against wear while delivering excellent protection against rust and corrosion. It is Warranty Secure® and will not void your marine engine's warranty.
Package sizes include:
1-Quart Bottle
1-Quart Bottles (case of 12)
AMSOIL 25W-40 Synthetic-Blend Marine Engine Oil is formulated specifically for Mercury motors that encourage the use of synthetic-blend oil. With this formulation, AMSOIL offers Mercury owners a superior choice who prefer to follow Mercury's synthetic-blend guidelines.
AMSOIL 25W-40 Synthetic-Blend Marine Engine Oil can be used in gasoline-fueled four-stroke inboards, outboards, inboard/outboards and personal watercraft that require any of the specifications listed below, including those made by Mercury* and Mercruiser*.
• API SM
• NMMA FC-W Catalyst Compatible
Protects Against Wear: Marine engines operate under high loads and rpm for extended periods. On average, a marine engine powering a boat 30 mph runs at about 5,000 rpm. In contrast, an automotive engine powering a car 60 mph runs at about 2,000 rpm. Higher stress causes traditional automotive oils to break down and lose viscosity. AMSOIL 25W-40 Synthetic Blend Marine Engine Oil is designed with excellent shear stability to deliver a consistent lubricating film. It helps guard engine components from wear for maximum life.
Marine engines are prone to rust and corrosion due to constant exposure to humid, wet environments. Rust on engine parts acts like sandpaper, scouring bearings, the cylinder wall, piston rings and other components, while aluminum pistons and other parts can corrode. Rust and corrosion reduce engine power
and eventually cause catastrophic failure.
Good rust protection is not natural to motor oil; it comes only by design. AMSOIL 25W-40 Synthetic Blend Marine Engine Oil is fortified with potent inhibitors that guard against damaging rust and corrosion.
• Excellent high-stress, high-rpm endurance
• Increased rust and corrosion protection
AMSOIL 25W-40 Synthetic Blend Marine Engine Oil is certified by the National Marine Manufacturers Association (NMMA) for use in four-stroke outboards, inboards, stern-drives (inboard/outboards) and PWC. This high-quality oil demonstrates outstanding performance and exceeds the NMMA "FC-W" (Four Cycle - Water) specification requirements.
• FC-W (CAT)® Registration Number: FC-11825T
* All trademarked names and images are the property of their respective owners and may be registered marks in some countries. No affiliation or endorsement claim, express or implied, is made by their use.
All products advertised here are AMSOIL-engineered for use in the applications shown.
Four-stroke outboard motors and personal watercraft: 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 once a year, whichever comes first.
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 WCM.
Keep out of the reach of children. Don't pollute. Return used oil to collection centers.
| TYPICAL TECHNICAL PROPERTIES 25W-40 Synthetic Blend Marine Engine Oil (WCM) API SM, NMMA FC-W Catalyst Compatible | |
| Kinematic Viscosity @ 100°C, cSt (ASTM D-445) | 16.0 |
| Kinematic Viscosity @ 40°C, cSt (ASTM D-445) | 139.3 |
| Viscosity Index (ASTM D-2270) | 155 |
| Flash Point °C (°F) (ASTM D 92) | 254 (489) |
| Fire Point °C (°F) (ASTM D 92) | 284 (543) |
| Pour Point °C (°F) (ASTM D 97) | -31 (-24) |
| Noack Volatility, % weight loss (g/100g) (ASTM D-5800) | 3.1% |
| Four Ball Wear Test (ASTM D 4172 @ 40 kgf, 150°C, 1800 rpm, 1 hour, Scar in mm) | 0.40 |
| Total Base Number (ASTM D-2896) | 7.9 |
| High-Temperature/High-Shear Viscosity @ 150°C, 1.0 x 106 s-1, cP (ASTM D4683) | 4.8 |
Product Name: 25W-40 Synthetic Blend Marine Engine Oil
Current Rating: 4.44out of 5 stars
Votes & Reviews: 8 vote(s) and 6 user reviews.
Reviewed by Bob: 
We use this product for a 60HP Mercury 4-stroke outboard motor. Love the product, and it is a great value also!
Reviewed by jherm1:
switched over from mercury oil to this...amsoil is the only oil I use for everything
Reviewed by Runky:
Switched my marine big block over to Amsoil 25w-40 and have seen better oil pressure and increased performance over 30w oil. I'll definetly use this oil again.
Reviewed by gofastman:
I purchased tis for my mercury, and i cant say enough about it, I have enjoyed using the amsoil product in everything i have and i will continue the use of it
Reviewed by gofastman:
I purchased tis for my mercury, and i cant say enough about it, I have enjoyed using the amsoil product in everything i have and i will continue the use of it
Canada
United States
Great value
Great value