Product Reviewed: SAE 10W-30 Formula 4-Stroke® Marine Synthetic Motor Oil (WCT)
Current Rating: 4.68 out of 5 stars
Votes & Reviews: 14 vote(s) and 34 user reviews.
Reviewed by James: 
I use this great lube oil for my 1990 Cruisers Esprit with twin Crusader 350's. I am never disappointed with this synthetic, even though they were designed for straight SAE 40. They run smooth and oil pressures are spot on.
Reviewed by Robert:
Fantastic no issues with this product will buy again and recommend it
Thanks
Reviewed by Andres:
Perfect oil
Reviewed by Bryan:
Great value
Reviewed by Triston:
Great product, love it
Reviewed by Russell:
Use Amzoil in all my cars and motorcycles, jetski's etc.
Never had an oil related failure.
Will continue to trust Amzoil.
Reviewed by Robert:
Great stuff. Boat runs way better.
Reviewed by Brian:
Great product when two outboards cost 50k you use the best product possible. Please make filters for yamaha outboards
Reviewed by Vic:
I recently started using Amsoil Marine in our Yamaha Jet Boat. With the boat being 6 years old, I immediately notice a quieter ride and was most impressed by the 5-7% thrust improvement (3-5mph). We will be using it in our jet skis next
Reviewed by RMC:
Excellent outboard motor oil, engine runs smoother and quit with this oil. I would recommend this product for all outboard motor owners. Best product out there! I live in Hawaii and I never got any free shipping or any free products. Thanks!
Reviewed by Bobby:
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!
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 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 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.
Canada
United States
My first boat. Amsoil is my only choice.
This is my first boat. It has a Yamaha 175hp SHO 4-Stroke. I have Amsoil in everything I own. After the breakin hours passed. I replaced everything with Amsoil. Motor,lower unit and bearing grease. It's the only oil for me. Always a Great choice.