AMSOIL 10W-30 Formula 4-Stroke® Marine Synthetic Motor Oil (WCT) 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 protects motors against wear, rust and deposits. It excels in both high horsepower applications and all-day trolling conditions.
Package sizes include:
1-Quart Bottle
1-Quart Bottles (case of 12)
55-Gallon Drum
AMSOIL Formula 4-Stroke® Marine Synthetic 10W-30 Motor Oil (WCT) is recommended for gasoline fueled four-stroke outboard, inboard, inboard/outboard (I/O) and personal watercraft motors. AMSOIL WCT motor oil is recommended for the following applications whenever an SAE 5W-30, 10W-30 or straight SAE 30 oil is called for:
Four-stroke outboard motors: Honda®, Mercury®, Yamaha®, Johnson®/Evinrude®, Bombardier/BRP®, Suzuki®, Nissan®, Tohatsu®
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-30 is recommended for use in place of 5W-30 as specified by Honda®.
NMMA FC-W • API SL
AMSOIL 10W-30 Formula 4-Stroke® Marine Synthetic Motor Oil (WCT) 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 protects motors against wear, rust and deposits. It excels in both high horsepower applications and all-day trolling conditions.
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-30011B 10W-30
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).
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).
• 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 WCT.
Keep out of the reach of children. Don't pollute. Return used oil to collection centers.
| TYPICAL TECHNICAL PROPERTIES | |
| AMSOIL FORMULA 4-STROKE® MARINE SYNTHETIC MOTOR OIL (WCT) SAE 10W-30, API SL, NMMA FC-W | |
| Kinematic Viscosity @ 100°C, cSt (ASTM D-445) | 11.7 |
| Kinematic Viscosity @ 40°C, cSt (ASTM D-445) | 74.5 |
| Viscosity Index (ASTM D-2270) | 152 |
| CCS Viscosity, cP @ (°C) (ASTM D-5293) | 6032 (-25) |
| Flash Point °C (°F) (ASTM D 92) | 236 (457) |
| Fire Point °C (°F) (ASTM D 92) | 258 (496) |
| Pour Point °C (°F) (ASTM D 97) | -48 (-54) |
| Noack Volatility, % weight loss (g/100g) (ASTM D-5800) | 4.8% |
| 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) | 10.5 |
| HTHS (cP) | 3.64 |
| Humidity Cabinet Rust (ASTM D-1748) | Pass |
Product Name: SAE 10W-30 Formula 4-Stroke® Marine Synthetic Motor Oil (WCT)
Current Rating: 4.67out of 5 stars
Votes & Reviews: 12 vote(s) and 22 user reviews.
Reviewed by West Coast Boater: 
Use it on both my Yamaha 2016 115 hp and 2017 9.9 high thrust motors.
Reviewed by Tomace:
Keep the motor cool and quiet
Reviewed by Chris:
Just recently bought a chaparral SSI sport bowrider boat took it out twice and got 47 miles per hour. change the oil to amsoil 10w 30 for boats take it back to the lake and ran it hard and got a solid 50 miles per hour.
Reviewed by Reeling:
I use Amsoil in my boat for the last three years. The engine seems more quiet and the oil level stays at the same level throughout the boating season.
Reviewed by Chris:
I bought a Seadoo GTR 215 supercharged unit and was looking for oil to complete an oil change. I've had great success with Amsoil in the past in sleds and atvs so I wanted to use in my Seadoo. I had read mixed reviews about using the Amsoil Synthetic marine oil in the supercharged skis due to supercharger clutch slip. But so far I've had no issues after approx 12 hours of riding.
Reviewed by Millerlite66:
I run this oil in a 1988 Glastron. I'm the second owner. I have used the 10w40 Marine oil for the 18 years I have owned this boat. It has a 7.4 liter GM big block in it . I have never had an engine problem that had to do with lubrication. Just sayin.
Reviewed by Mitchell:
Can't tell the difference.
Reviewed by Louie:
Oil I could trust running offshore
Reviewed by Mismo Titan:
We run our sea doos hard and this oil has never let us down. For supercharged skis there are no friction modifiers and it's JASO MA2 which is safe for our superchargers. I've been running amsoil in all my products for a while now and won't run anything else.
Reviewed by Jeff:
Good product, quick delivery, nice website, I'm a fan of Amsoil.
Reviewed by Reggie:
Developed for Outboards; oil is cleaner after use than regular oil
Reviewed by Bobo0415:
Better than Mobile 1. Increased top end, engine runs more smooth at idle. Don't waste your time buying oil from the outboard manufactures, over priced and over rated. Amsoil exceeds Suzuki requirements and will not void warranty. Bought a case, saved on the shipping.
Reviewed by DonV:
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.
Reviewed by Showman:
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.
Reviewed by 4 to 1:
Yam sport boat
Reviewed by 4to1:
Yam sport boat
Reviewed by erictm:
Using it in my third engine with great results. Not a repair one on the first two. Keeps engine very clean.
Reviewed by matt:
having a $15k investment and protecting it starts with Amsoil. I use it in everything I own an have had ZERO problems.
Reviewed by tootall:
Use in my 150HP and 9.9HP Suzuki Outboards
Reviewed by Ronald:
I have been using this in my 4 strokes for 10 years- first in Honda 130's and now in Yamaha f250's. I have used Mobil 1, Honda and Yamaha oils and the amsoil is always cleaner at the end of the season and still has a goldish brown color.
Reviewed by James B:
Switched to 10W-30 Formula 4-Stroke marine oil in a Honda BF115 2.3L outboard motor and immediately noticed reduction in engine noise. It hums along much more quieter in all rev ranges, its just that much more smoother to operate this motor. The fuel economy is also better, able to go further with the same amount of fuel. All of it indicating one thing... reduction is internal friction! Will continue to use this product.
Best for my boat!
I have been using this in my Yamaha 150 4 stroke for over 10 years. I recently replaced the balancer and had the opportunity to inspect the engine internally from the bottom end. I observed absolutely zero wear on visible internal engine parts and the engine was so clean inside it looked brand new!