What octane does everyone run in their 4 strokes?

We have always had 2 stroke engines, but finally entered the 4 stroke world. Just wondering what you guys run in terms of gas and even the type/brand of oil you use?

Non Oxygenated Ethanol-Free gasoline
http://www.drillnowhere.com/non-oxy-fuel-list/minnesota.html

87 octane and Mobile 1 synthetic.

87

Whatever the non-oxygenated ethanol free gas is. I don’t think octane rating really matters. In the past I have used 87-92 octane and never noticed a difference. The Yamaha has been corn free and problem free for 6 yrs now.

87 in both yammies!

I used to always run Non-Oxy 90-91. 2 years ago I started running regular 89. I think my Offshore 300 runs better on 89 then 91 plus it doesn’t hurt the pocket as bad. Yamaha has the motor made to run 89 with up to 10% ethanol, why not run it. I also run Yamaha Ring Free and Fuel Stabilizer/Conditioner.

Does the user manual actually say to run non-oxy. I’d be shocked if manufacturers didn’t put the proper seals in a motor made after 2010.

The only reason for non-oxy is because the seals in older motors would deteriorate from the ethanol.

In the past I’ve always ran 87 in my Yamaha’s & Yamalube oil. This year I enter the Off Shore world with my new 250 XCA. We’ll see what the book says I always go by what Yamaha tells you to do. You’ll love that 4 Stroker !!!

The yamaha motors only require either 87 or 89 oct fuel. The sho’s and offshores require 89 oct and the rest only require 87 oct. These engines were designed to run up to 10% ethanol. Do follow the recommened oct rating though as it will de-tune your engine if you are running less than required.

What about running non oxy 91 premium. Should be good to go?

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What about running non oxy 91 premium. Should be good to go?

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You wont hurt anything by any means, just spending more money than you need to. It wont increase performance or anything like that.

Running a higher then called for Octane rated fuel “can” be more harmful. Higher Octane fuels burn slower, lower compression engines will create more carbon inside cylinders because they can not burn the fuel cleanly and leave more residue in the cylinders.

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What about running non oxy 91 premium. Should be good to go?

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If the engine is not designed to run 91 it will only build carbon. All of the yamahas are made to burn up to 10% ethanol. The only engines that require 89 octane are the SHO 150, 225, 250, the f200 lightweight, the f250 3.3 liter, the f300 4.2 liter offshore and the f350 v-8. Everything else runs on 87 octane.

I have an F300, not really a fan of ethanol. Can I fill half the tank with 87 and the other half with 91? All the 89 is ethanol.

The engines and the components in the engine are designed to handle it. You just need to keep up on the maintenance of your filters because they are going to trap water and other contaminants. They are what is protecting your investment. Mixing the fuel doesn’t seem to me like that is a good idea. If the octane isn’t correct the engine will detune itself so that detonation doesn’t occur and ruin the motor.

Sean- Do you know of anyplace around here that sells 89 octane without ethanol? I’ve been running 91 because that’s all I can find around here that’s ethanol free. If it were up to you, would you run 89 with ethanol, or 91 without in my 300?

Here’s a quote word for word from my F300XCA manual “Yamaha recommends that you use alcohol-free gasoline (see Gasoline with Ethanol) whenever possible”. It really doesn’t say anything about using higher octane though; it just lists 89 as the minimum.

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What about running non oxy 91 premium. Should be good to go?

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If the engine is not designed to run 91 it will only build carbon. All of the yamahas are made to burn up to 10% ethanol. The only engines that require 89 octane are the SHO 150, 225, 250, the f200 lightweight, the f250 3.3 liter, the f300 4.2 liter offshore and the f350 v-8. Everything else runs on 87 octane.

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I’ve seen 89 octane ethanol free at Fleet Farm before. I think it might be a seasonal thing as it disappeared a few weeks later. I’ve noticed this at other gas stations too. They might have 87 and 89 with E10 in the summer but come winter they are both 10% ethanol blends.

Most of the newer engines won’t have a problem with 10% ethanol in what ever octane is recommended for you outboard. I would defiantly recommend treating your fuel with stabilizer if you don’t think you are going to use it with in about 30 days after you get it, to prevent it from breaking down.

For oil I would recommend using Yamalube 4M but if you want to use a different oil the big thing is to make sure its an FC-W rated oil. These oils are formulated specifically for outboard engines to help prevent condensation that will often occur from standard motor oil.

Been using 91 non ethynol fuel in boat and small engines (2 stroke or 4 stroke) for over 35 years and have never had a fuel problem.