91 octane no ethanol vs. 87 octane w/ethanol and treatment.

[ThreeMileBayWaker]

I have a 10' 4.3L GL-J and have always ran normal 87 pump gas with the marine sta-bil ethanol treatment with every fill up.

My local gas station now carries 91 octane with no ethanol, I'm not looking for HP gains but rather less stress on the carburetor gaskets and seals. Would it be proactive to switch to the 91 or just keep running the 87 with the marine additive to combat the ethanol?

 

[Bondo]

Re: 91 octane no ethanol vs. 87 octane w/ethanol and treatment.

Ayuh,.... I saw the sign at nice, 'n easy,... Movin' this to the non-repair forum,...

It's got the makin's of another "Oil Thread",....

 

[MWG2600]

Re: 91 octane no ethanol vs. 87 octane w/ethanol and treatment.

run whichever is cheaper.

 

[ondarvr]

Re: 91 octane no ethanol vs. 87 octane w/ethanol and treatment.

run whichever is cheaper.

And skip the ethanol treatment, at least using it all the time.

 

[Silverbullet555]

Re: 91 octane no ethanol vs. 87 octane w/ethanol and treatment.

With how new your boat is, the engine itself will be fine with the ethanol.

That being said, I do everything I can to keep ethanol out of the boat. I found a local place that carries ethanol free in all grades and we have a couple more that carry ethanol free in 87. To get access to all the grades I had to join their cardlock and I have to use 25 gallons a month. It was worth it to know that I can get ethanol free for the boat and for the old suburban. Plus I get discounts on other chevron products (delo, etc).

It's not going to hurt your boat to run 91, but it will hurt your pocket book.

 

[Another retired guy]

Re: 91 octane no ethanol vs. 87 octane w/ethanol and treatment.

If you use your boat regularly just go with the basic 87 and don't worry about the ethanol, and don't bother with the additive.
If your boat sits unused for months, then add the treatment.
91 octane won't give you any noticeable power increase.
Adding some 91 to the tank before long-term ( ie winter) storage will help maintain octane level of the mix.
This is what I do, and have had no fuel related problems at all!
Other people will have different opinions. Bottom line is it doesn't seem to matter what fuel or additive you use.

 

[ThreeMileBayWaker]

Re: 91 octane no ethanol vs. 87 octane w/ethanol and treatment.

I haven't had any fuel problems either, but my boat does sit for a while between uses. It's a battle up here in NY to get days off from work that have nice boating weather, I average about 30-40 hours a year on the boat.

Guess ill just stick to what I've been doing.

 

[matt167]

Re: 91 octane no ethanol vs. 87 octane w/ethanol and treatment.

Ethanol fuel can last a couple months of sitting with no real issue so as long as you run the boat thru the season 87 will be fine, but my advice is to run 91 ethanol free as the season ends as the gas will last longer and be fresher for next year. Some store tanks full, some store tanks low/ empty. If your going to store low/ empty make sure what is in there is ethanol free.