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10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)

 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
Product Code: WCF • Brand: AMSOIL

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

See Pricing or Place an Order
MSDSData Sheet

Product Details

Product Applications

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.

Mixing AMSOIL

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.

HEALTH & SAFETY

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.

Technical Data

TYPICAL TECHNICAL PROPERTIES
AMSOIL FORMULA 4-STROKE® MARINE SYNTHETIC MOTOR OIL (WCF)
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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 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)

Did this product meet your expectations?

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Product Name: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
Current Rating: 4.89out of 5 stars
Votes & Reviews: 41 vote(s) and 24 user reviews.


A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by DonV: space

Only the best

This was my first oil change on my new outboard. I really never considered any other oil. I also used this same oil on the last 4-stroke outboard I had and it performed perfectly.

Item Reviewed: Four Stroke Marine Motor Oils (WCF,WCT)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Showman: space

Great oil

I started using amsoil in my Yamaha because I did not have hour meter to keep track of hours thinking amsoils superior oil would give me some forgiveness if I went a little over recommend hours. I added hour meter, will still use amsoil under preferred customer plan.

Item Reviewed: Four Stroke Marine Motor Oils (WCF,WCT)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Trotline: space

I would use nothing else

I use this in my 50hp 4- stroke and you could immediately tell a difference. It ran much smoother and quieter.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Mike: space

Would not put anything else in my yacht.

Great marine oil. Use it in the boat and jetskis.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by mdd: space

works great n my boat

I've added this to my marine inboard motor and seems to be running very well

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by John: space

Great product! Highly recommend it...

Outstanding product...

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by John R.: space

Will continue to use it

I have used the 10w40 Marine oil in my Yamaha Waverunner for awhile and to date just great results.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by John R.: space

Will continue to use it

I have used the 10w40 Marine oil in my Yamaha Waverunner for awhile and to date just great results.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Paul - boater: space

Going to use this for first time with high expectations

Installed in both of my 8.1L Mercruuser engines on my 40' Boat. Also going in my generator. Hope to get the advertized results.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Reg: space

In all Mercury four strokes

I have ued this in my 115 mercury efi fourstroke and also my 150 efi fourstroke. Now I use it in my Mercury 225 Verado. Best oil to use here in Canada . No more hard starting when the température gets down close to freezing and a great remplacement for Mercury 25-40 semi synthétique oil.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by R: space

Oil for my PWC

I like the product, oil seems to be better then YamaLube, Stays clear longer, while YamaLube becomes non transparent and dark grey almost black within 10 hrs. Have AmsOil in high RPM SVHO engine for 35 hrs now and its still clear and light yellow color.

However overall purchasing experience was less the pleasant.

First, even though the address was correct, they did not ship on time because they could not read the address properly, then the courier didn't know what to do with the package.
So because of that it unnecessary took long time to receive the product.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Dennis: space

Great for Sea-Doo

Works great in my supercharged Sea-Doo. No issues with supercharger slipping, motor runs very smoothly. Will continue to use this.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Crusiers inc: space

The best their is

I use this oil in my 7.4 liter mercrusier motor. Now Amsoil and Mercrusier recommended that I use the 20w 40 synthetic blend. But I wanted full synthetic. This oil is AWESOME!

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Lou: space

Great For High Revving Outboards

Have always used the 10w-40 and 10w-30 marine 4 stroke in my outboard and wave runner engines. Very confident that it holds up well to the high revs.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by MrEd: space

Multiple motors

I use Amsoil in my:
2008 M-Benz V-6 diesel (meets the 229.51 spec.);
2017 Subaru 2.5 normally aspirated 4 cylinder boxer (0W-20 Signature Series);
2013 Yamaha 90 hp outboard;
1999 Honda V-2 10kw generator;
pressure washer, and lawn mower.

I change oil in all these motors once a year, along with an Amsoil filter for the Forester.
I switched from M____ products to Amsoil after I personally compared the specs for 5 quality motor oils, including the "Subaru" oil (actually Idemitsu Oil) and found that Amsoil matched or was better in most of the parameters on all the oils, particularly the NOACK value (for volatility or "boiling off".) I was especially interested in the 0W-20 values, since I had a chance to choose a specific oil to use in the new Forester for its life. I found that there was a huge NOACK difference between Amsoil and the Subaru/Idemitsu oil. No doubt that is why Subaru recommends a 6,000 oil change interval, and Amsoil Signature Series is at 25,000 miles. None of the other oils matched Amsoil's NOACK value. That comparison convinced me. At 500 miles I drained the Subaru/Idemitsu oil and switched to Amsoil Signature Series, and changed it again at 6,000 miles and am now on a yearly change cycle, since I average between 10,000 and 13,000 miles a year. Cheaper and better - a no brainer.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Don the Biker: space

The best engine oil

AMSOIL is the only engine oil I will use in my vehicles, motorcycle, and outboard motor. It improves the gas mileage on my Victory motorcycle by over 10% compared to OEM synthetic oil. That convinces me that there synthetic oil reduces engine friction and should help the engine last longer.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Daniel: space

Good oil

Best four the marine motor, always I used to my cruiser and bow rider, awesome performance

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by DANIEL: space

Only oil for my outboards

Only oil my Outboards will ever see. One great oil

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by James: space

I will always use this product. Very satisfied.

I use this product in a 2013 mercury 150hp 4 stroke outboard. It runs great with no issues. Living in the northeast our season is short so I can only get about 75 hrs of use. My only issue is that you do not make an oil filter for this engine.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Brbstafford: space

I run only Amsoil

Have this in my new Waverunners after break in for winter storage.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Brian: space

I run only Amsoil

Have this in my new Waverunners after break in for winter storage.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Brad: space

2nd to none

Outboard

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Flattop: space

Revived engine performance

I thought I'd try Amsoil Marine 10W-40 in my 23ft I/O that has a GM 350 CID engine. After changing the oil it felt like the engine had gained 30-40 HP. It gets on plane easier, revs faster, and runs as cool or cooler that the 15W-40 diesel oil That was recommended by the marina mechanic. Additionally the oil seems to stay cleaner longer. I just can't see a down side to this oil. It's all good. Pulls my grandchildren on their tubes and skis easier and gets up to speed faster even with a load. Great product.

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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A Verified Buyer is an individual who has purchased the reviewed product and submitted their review through a specific process that tracks purchase history.Reviewed by Jeff: space

Great product.

I ran this in my mercury optimax 125. It ran cleaner and smoother than when running on the mercury oil!

Item Reviewed: 10W-40 Synthetic Formula 4-Stroke Marine Oil (WCF)
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