Synthetic oil in a four stroke outboard motor

[RcgTexas]

Anyone using synthetic such as "Mobil 1" in their 4 stroke outboards?

Thinking of doing it just wondering.

[ralph]

I'm using the Yamaha brand of synthetic oil while under warranty. Perhaps after the warranty is out I will switch.

[Bamaman]

Mobil 1 has never been "certified" for marine use. That tells me that Mobil/Exxon has chosen to never spend the money to have the oil tested and certified because the marine oil market is tiny in comparison with the auto/truck retail market. It's as good or higher quality oil than anything Mercury or Yamaha sells. We all know marine manufacturers are oil retailers, not manufacturers.

That said, I changed my oil 2 years ago with Mobil 1 Extended Performance--a superior oil to plain ole Mobil 1. When I changed oil (to Mobil 1 EP) yesterday, the old oil looked like brand new. Five quart jug at Walmart was $25--about the same as 2 1/2 quarts of YamahaLube. I also changed the oil filter on my Yamaha F150 to a Motorcraft 900--same filter as the much more expensive Yamaha filter.

At 20 hours, I changed oil, and I wanted to run dino oil one time in case the engine had not been completely broken in. After reading on BobIsTheOilGuy.com, I used Rotella diesel/universal oil. While you don't want to use it in any engine that has a catalytic converter, it does a great job in 4 stroke outboard motors and it's very cheap @ $3 per quart.

[RcgTexas]

The service classification meets the guidelines per the service manual so I think I will try it. Thanks for the replies guys.

[rancherlee]

I'm running Mobile 1 Highmileage 10w40 since its one of the few 40W oils they offer and that's the important number when considering oils, suzuki wants 10w40. The first number is not important on engines that don't see below freezing use so I try to get one that has the LEAST amount of "stretch" between the numbers. I say stretch because that's what it is, the further the numbers apart, the more non-lubracative additives needed to "stretch" between those numbers.