Oil for Yama 115/80 jet 4 stroke

[Hi-Liter]

I have a newer Yama 115/80 hp 4 stroke on my sled. I have changed the oil before using Delo 10W-40. Is a synthetic oil good or just stay conventional? any suggestions? Thanks

[Rick]

My buddy's and I all run Rotella 10w-30 in our outboards.

Thats a handful of Yamahas and a couple Suzukis.

[L-ofalab]

I thought Delo was for diesel engines, I run Delo 400 in my Cummins.  Rotella is also made for diesels. Why are you using oil made for diesels? Is that common?

[Rick]

I thought Delo was for diesel engines, I run Delo 400 in my Cummins.  Rotella is also made for diesels. Why are you using oil made for diesels? Is that common?

Delo and Rotella are both dual rated (gas or diesel) heavy duty engine oils.

As long as they meet the manufacturers viscosity requirements, They're perfect in a four stroke application.

[Tman]

I have the an 04 115/80 jet . Use mobile 1 full synthetic with a napa filter and have never had an issue. Plus it's about 80 bucks cheaper than oem.

[L-ofalab]

This is what the Yamaha site says-


May I use Automotive Oils in my four-stroke Yamaha Outboard?


No. Automotive oils are not designed for the operating conditions four-stroke outboard motors face, particularly moisture, cooler operating temperatures, and extended full-throttle operation under load. Oils for your car do not contain, for example, sufficient quantities of the superior rust and corrosion-resistant additives found in quality FC-W™ oil. Oil with the FC-W™ rating from the NMMA® has been specifically formulated for the tough marine environment. Yamalube® 4-M FC-W™ meets or exceeds all FC-W™ requirements

[Rick]

This is what the Yamaha site says-


May I use Automotive Oils in my four-stroke Yamaha Outboard?


No. Automotive oils are not designed for the operating conditions four-stroke outboard motors face, particularly moisture, cooler operating temperatures, and extended full-throttle operation under load. Oils for your car do not contain, for example, sufficient quantities of the superior rust and corrosion-resistant additives found in quality FC-W™ oil. Oil with the FC-W™ rating from the NMMA® has been specifically formulated for the tough marine environment. Yamalube® 4-M FC-W™ meets or exceeds all FC-W™ requirements

Imagine that...Yamaha wants you to use an oil with their name on it.

I wonder if it has anything to do with them buying it for $1 a qt and selling it to the consumer for $10?

I've seen oil analysis from virgin and used "Yamaha" oil. Its nothing special.

The F300 on the back of my boat runs about $25K. If I didn't think Rotella was appropriate ,I wouldn't be using it.