Yamaha recommends changing engine oil every 100 hours or yearly on their SHO outboards. Using the Amsoil marine oil I am amazed how clean the product looks with that many run hours when changed. After removing the OEM oil from my motors and switching I noticed smoother operation when idling and lower overall temps when making long wide open runs. Based on my experience over the last 8 years running the marine oil several friends with Mercury and Suzuki motors have switched recently and their comments echo my own.

The factory oil my outboard calls for was looking like it came out of a diesel after 50 hours. This Amsoil stays much cleaner and that gives me piece of mind.

It looks to work great for me on the jet ski.

I've been using Amsoil synthetic oil in every machine I own for the last 10+ years. Lawnmower, jetskis, 4 wheelers, 3 vehicles. I'm convinced it is the ultimate oil choice.

Been using 10w40 marine oil for 3 years now won’t trust any other oil for my 5.7L I run hard and sometimes long to get to the fishing grounds I don’t wanna worry about oil and I never do with Amsoil great stuff

Why not use the best oil available for hour expensive toys. My boat motor is worth it.

Good stuff

I have been using AMSOIL in all of my motor vehicles. My boat runs super smooth with this synthetic marine oil and I would highly recommend to anyone who is looking for new oil. Cannot beat the quality.

First oil change on the waverunner and wanted to go full synthetic to ensure that my expensive investment lasts for years to come.

Seems to be the best for the engine.

I have been using this oil for years And very happy with it

I only have 5 hours on ur oil in my 4 stroke used Yamaha so have not put it to the test ! However I have used it in my Indian motorcycle some years back and would say that it never failed. I have friends who swear by it. I believe it to be superior oil.

Quality product, have used it for years and no issues.

I have trusted this oil in my Volvo Penta 5.0 V8 for many years, and in my Mercruiser 5.7 V8 before that. These engines always started and ran perfectly. Great protection.

I ran it in my 4.3 mercrusier and it worked great, I am going to run it next year also

Good for smaller trolling motors without oil filters

I am using this on a 2017 Mercury 115 four stroke. I like the idea of having extra protection from a full synthetic, especially in tough marine conditions.