89 octane fuel for F300 Yamaha outboard 2023

[RTS14]

It seems many if not most marinas (including Cap Sante in Anacortes and LaConner) now only sell ethanol free 87 octane gasoline. Yamaha specifies '89 octane' fuel. They don't specify if this is RON+MON/2 (research and motor octane average) or something else. Evidently Yamaha does not specifically require to be ethanol free.
If 89 octane is the Yamaha recommendation, what occurs if there is a warranty claim for engine failure and Yamaha refuses the claim due to the use of inadequate octane fuel?
Is there anything an owner can do, given the aforementioned fuel availability limitations?
Thanks

 

[BB marine]

There is information posted about this on the Yamaha Forum. The best place to get the answer you need is to go to a Yamaha servicing dealer and talk to a certified Yamaha technician factory trained. I believe that he/she will tell you your warranty will not be affected by the use of no ethanol 87 octane fuel. He/she may also tell you that you may not get peak performance when using the lower grade octane. The performance will be similar to what a 250hp delivers. That is “the word on the street”. I would get the word from the guy that is servicing and warranting the motor.

 

[Submariner]

There are knock sensors in the engine that will downgrade the performance of the F300 accordingly to prevent damage from running 87 octane fuel. So no harm in running 87 octane gas.

Ethanol is an octane booster.

89 octane fuel with 10% ethanol is actually 87 octane fuel. The 10% ethanol raises the octane to 89. Then when the ethanol sits for awhile and separates from the gas in your tank, then absorbs the water... bad things can happen.

I'd rather run 87 ethanol free octane fuel than 89 octane fuel with 10% ethanol.

I've got over 750 hours on my F300, 3/4 of those hours were all done with 87 ethanol free gasoline.

During the off season, it's important to have your gas tank either mostly empty or mostly full. Never in the middle. If the tank is mostly empty, there's lots of air in the tank but little gas (or ethanol fuel) to absorb water from the air. If the tank is mostly full, there's not a lot of air in the tank for moisture to be absorbed from. Also don't forget to add fuel stabilizer for off-season storage.

During our SE Alaska trip, going through Canada, one of the reasons I found gas in Canada to be so expensive is that they only sell premium grade fuel (89 or higher octane) and ethanol free. There was a letter attached to the fuel pump at French Creek fuel dock. It stated that Canada passed a law requiring all mid and low grade fuel to have ethanol. So to get ethanol free fuel on the fuel dock all they could do is sell premium grade gasoline.

I've ran 1 tank of fuel through Channel Surfing that was 10% ethanol. (Point Roberts fuel dock only offered ethanol gas). I didn't have a choice as I needed gas to get home and all that's all they had. It's not a big deal to run ethanol fuel as long you burn it within a week or so. Don't let it sit in your tank for long periods of time.

Most of the gas stations throughout SE Alaska all had premium gasoline that was ethanol free.

In Puget Sound and the San Juan Islands, Oak Harbor and Des Moines are usually the least expensive. Both are usually 89 octane ethanol free. Point Roberts and Coupville are 10% ethanol. Friday Harbor gives you the choice of "clear gas" (non-ethanol) vs regular gas (ethanol). Most everybody else in Puget Sound and the San Juan Islands is 87 octane non-ethanol gas.

 

[Submariner]

He/she may also tell you that you may not get peak performance when using the lower grade octane. The performance will be similar to what a 250hp delivers. That is “the word on the street”.

That's what I've always heard myself. After running my boat for 500 hours using mostly 87 octane ethanol free gas, then I took my boat to SE Alaska and found that most of the fuel docks were giving me mid-grade or premium ethanol free gas.

I asked several attendants what the grade of fuel was (Wrangel, Alaska, being one of them). Petro Marine is the primary fuel supplier throughout SE Alaska. It's' all mid-grade ethanol free they said.

180 engine hours in 6 weeks on mostly mid-grade or premium gas, I couldn't tell a difference between the 87 octane fuel I run in Puget Sound and the San Juan Islands.

 

[BB marine]

180 engine hours in 6 weeks on mostly mid-grade or premium gas, I couldn't tell a difference between the 87 octane fuel I run in Puget Sound and the San Juan Islands.

I would not expect to see a difference. A boat powered by two 300's that cruises at 40mph and has a WOT speed of 55mph running light and turning 6000 rpm may see a slight difference at top end when the engine is making full rated HP. The 225,250 and 300 are all 4.2 L engines with the same compression 10.3 to 1 hence the knock sensors. All of them have knock sensors. All of them retard timing based on knock sensor information sent to the ECU. Ignition knock "detonation". The use of a higher octane fuel can help reduce this along with different fuel/air mixtures and many other perimeter changes that the ECU makes. The 300 hp is Yanmar's 4.2L performance engine. It is tuned to make 300 hp by changes in the ECU ignition timing, valve timing and throttle plate positioning (fuel/air). A rule of thumb is one number higher in octane will allow for 1 degree of advance before knock.

Example: I had a Mercruiser 350 mag in a 19' Pachanga Sea Ray. It was a fun little boat to play in.Standard base timing 8 bdtc used with 87 octane . If I put 93 octane in the tank and planned on running it hard. I would get a slight noticeable difference in top end when I set the base at 12 bdtc . This engine did not have knock sensors so if it detonated I would hear it. I felt safe doing this if I used a good known gas rated at 93. Most of the time I left the timing at 8 BDTC.

Yamaha did the same with the 300 hp, advanced total timing an additional 2 degrees to get the engine to reach full rated HP. 2 degrees advance with 89 octane may give you as much as 10 hp at rated hp rpm. Under perfect conditions with the engine mounted to a boat that can get up and go. You may feel the slight difference between 87 octane and 89 Octane. I truly believe the only way you would see a measurable difference is if you had two engines hooked to a Dyno one running 87 and one 89. The dyno would measure the difference comparing apples to apples.

As I stated before a good factory certified Yamaha technician should know what the differences are in timing ,valve timing and throttle position. If you need to know that.

 

[dgiles]

Some of the concerns here regarding ethanol in your fuel is a bit laughable. Need to burn it within a week or two? Really? While marine fuel applications on the water typically have had a ethanol free option, elsewhere in many parts of the country, all you can get is ethanol in the fuel. And if your boat only needs 87 octane, why would you pay another $0.80/gal to get ethanol free premium with octane you don't need? How many boat forums are overun with "water in the fuel" issues due to ethanol or fuel storage issue? Very few. When you get water in the fuel, it is usually due to actual water getting into the fuel from the fuel delivery. 90% of the boat storage people on lake boats here use good ole' 87 octane with ethanol and store them all winter with stabilizer and all seem to fire up fine in the spring, year after year.....