Yamaha 115 four-stroke lubrication questions....

[BullyT]

I am a strong believer in synthetic lubricants and use them in all my vehicles. I have a 2002 Yamaha 115F outboard (low hours on it) and I've been using conventional 10w30 oil as recommended. For my next change, I was going to switch to 10W30 synthetic. Is there anything unique to an outboard that would preclude the use of synthetic oil?

In addition, the gear oil for the lower unit is spec'd as SAE 90W which is what I've been using. I was going to switch to 75W90 synthetic. Are there any issues with that? Sorry for the "newbie" questions...

 

[Turk]

I've ran Amsoil 4-stroke Marine the last 2 seasons and my 140HP engine sings with it in !! Amsoil's Lower Unit Oil is great also.

High recommendation!

 

[rokky]

Although some manufacturers do not specify marine lube for the lower unit, I would consider it due to its ability to resist fresh or salt water contamination.

 

[dwendt44]

Most marine engine makers shy away from synthetic oil.
Basic reason is that syn. doesn't have as much corrosion
protection as regular mineral oil.

The gearcase will do well with the synthetic, though.

 

[Turk]

Amsoil has great corrosion additives.

Pablo, chime in??

 

[Steve S]

so do all the HDEO'S

 

[Slick 55]

If I had a big, four stroke outboard there would be nothing in it but Amsoil. Their marine oils are worth the money.

 

[Steve S]

Running syn won't hurt anything try it .

 

[Pablo]

Sorry for chiming in late. I just started reading this thread to see what's up with Yamaha.

By default HDEO's have a decent amount of steel corrosion inhibition via the additive package. However, purpose made marine oils should have very specific organic and inorganic additives for various engine alloy protection. Nothing wrong with switching to synthetic, just look for an oil such as:
Amsoil WCT 10w30

For the lower end: Amsoil Marine Gear Oil