Thread: Gas in oil in Yamaha 115 4 stroke

Usually when you run any kind of motor the oil will read higher on the dipstick due to the oil moved within the engine. Check your oil level cold and see what it reads and also the viscosity.

I would check the fuel pump first to see if it is bad.

It also could be that the engine was running “too cold” on the muffs and stayed in cold start mode. if this is the case a thermostat change might be the solution.

I am just a shade tree fella so a visit to the boat shop might be warranted if ur head is spinning.

Good luck!

Do a search for making oil, you will need to change out the oil as it is diluted with fuel and will not protect your engine as designed

Originally Posted by Bricks

Do a search for making oil, you will need to change out the oil as it is diluted with fuel and will not protect your engine as designed

Yep this. I ran a 90 from the same engine family on my last boat. I never had any problem with mine, but I remember reading a lot about the “making oil” deal


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Originally Posted by J White

Yep this. I ran a 90 from the same engine family on my last boat. I never had any problem with mine, but I remember reading a lot about the “making oil” deal


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Usually caused by the engine not being run hard enough to get the engine up to temp, and why would you run it on muffs for a couple of hours?

Originally Posted by Bricks

Usually caused by the engine not being run hard enough to get the engine up to temp, and why would you run it on muffs for a couple of hours?

My thought too.....

4 stroke outboards seem to "make oil" more than other 4 strokes. Maybe its due in part to the vertical design...idk really. But you will need to change the oil for sure as well as the filter. It shouldn't have caused any damage and should be good to go after that.

If I ever plan on idling a long time in my 4 stroke, like scanning structure or mapping, I make sure to fully warm up the engine first by running it hard. I also try to avoid idling for more than about 20 minutes at a time.