Does High Octane Fuel Store Longer?

For years I have been reading many articles including this one, that say the higher the octane fuel, the more stable it is, therefore in storage it lasts longer per se. You’re saying that’s not true?

It might be dependent on how the octane rating is achieved. But there is no stability difference that would be dependent on the branching of the octane molecule. Highly volatile compounds added to octane to increase the rating might be affected over time.
 
Think of a fuel's octane like you would a lubricant's friction coefficient. You can use different base oils to improve the dynamic friction coefficient just like you can use different base material to improve octane. You can also use additives to improve dynamic friction coefficient just like you can use additives to improve octane. Does the increase or decrease in a lubricant's friction coefficient have any direct correlation with its Noack volatility, foam stability, rust inhibition, detergency, wear protection, cleaning ability, etc...? No. It's the same way for the octane rating of a fuel. It's not directly correlative to power, storage life, detergency, flame speed, etc... It's a highly valued parameter, but is just one parameter.

Premium pump gas will tend to have better shelf life, but it's due to having a higher initial boiling point and more aromatic content, not due to the octane rating itself. You could formulate a regular pump gas with the same IBP and aromatics, reducing higher octane alkanes and alkenes to compensate, and it would be just as stable. (not that you would want to do that) I guess what I'm saying is while premium tends to have a better shelf life, it's not due to the octane rating, and likely varies more between seasonal blends than it does between premium and regular.
 
Please cite your references stating that isopropanol behaves any differently than ethanol in this regard.
It's kind of hard to prove a negative... There is a huge amount of research on drying out production ethanol, that only makes sense when applied here if you're already a chemist. I'm not going to get into definitions of minimum azeotrope, you can look up salting-out, entrainers and other physical properties.


Anyway, compare these two descriptions. Only one describes being soluble.


"The isopropanol does not remove the water from the gasoline. Rather, the isopropanol solubilizes the water in the gasoline. Once soluble, the water does not pose the same risk as insoluble water as it will no longer accumulate in the supply lines and freeze."
vs

 
The user can not know for sure which grade of gas stores best because of three unknowns 1)date of manufacture 2)time stored at the station 3)tank mixing contamination...
 
What brand of gasoline are you using? I've never had an issue in over 30+ years with Chevron.
Usually Exxon or Shell .

The best place to get history of Ethonal damage is a small engine repair shop, they will normally have a large pile of machines, with not worth fixing ethonal damage, the customer had rejected the repair cost.
 
Usually Exxon or Shell .

The best place to get history of Ethonal damage is a small engine repair shop, they will normally have a large pile of machines, with not worth fixing ethonal damage, the customer had rejected the repair cost.
I've been running E10 in my 35 year old Craftsman lawn mower for the last 25 years (when that's all I could get) and have never has a problem with the carburetor.
 
Ethanol can and does damage certain aluminum alloys and rubber fittings. For those who have never experienced that, you are fortunate.

It is my understanding that non-ethanol gasoline is kinder to aluminum and rubber, but it still goes bad in time.

There are quite a few people promoting the myth that premium fuel lasts longer, several in this thread.

Last year I used premium in my motorcycles for the winter months when I ride less. I didn't have any carb or fuel injector problems last year, but I started this thread because there's so much contrary advice out there.

I think I will use regular gas this year and keep it dosed with Stabil. Maybe hit it with Techron next Spring when I do my post winter oil changes.
 
Ethanol can and does damage certain aluminum alloys and rubber fittings. For those who have never experienced that, you are fortunate.

It is my understanding that non-ethanol gasoline is kinder to aluminum and rubber, but it still goes bad in time.

There are quite a few people promoting the myth that premium fuel lasts longer, several in this thread.

Last year I used premium in my motorcycles for the winter months when I ride less. I didn't have any carb or fuel injector problems last year, but I started this thread because there's so much contrary advice out there.

I think I will use regular gas this year and keep it dosed with Stabil. Maybe hit it with Techron next Spring when I do my post winter oil changes.

Ethanol is actually quite compatible with elastomers including tigon. It is also neutral to aluminum. Aromatics like toluene, xylene, and ethylbenzenes are more corrosive to aluminum and rubber than ethanol, and they make up 20+% of pump gas.

 
Ethanol is actually quite compatible with elastomers including tigon. It is also neutral to aluminum. Aromatics like toluene, xylene, and ethylbenzenes are more corrosive to aluminum and rubber than ethanol, and they make up 20+% of pump gas.

This article claims "vehicles made after 1993" are able to use e85. Does that include motorcycles?

My Nissan Versa was made in 2015 but the owner's manual specifically states not to use any e-fuel with more than 10% ethanol in it. That would include e15 and e85.
 
This article claims "vehicles made after 1993" are able to use e85. Does that include motorcycles?
If that was true, I'd think the owner's manual (1994 and beyond) would say that up to E85 is OK to use. My 2005 Tacoma and 2000 Hayabusa OMs say up to E10 is OK, nothing more.
 
This article claims "vehicles made after 1993" are able to use e85. Does that include motorcycles?

My Nissan Versa was made in 2015 but the owner's manual specifically states not to use any e-fuel with more than 10% ethanol in it. That would include e15 and e85.

Seeing as the quoted source is selling E85 capable kits, I would seriously question that. Only the Flex fuel capable vehicles from manufactures for some years are designed to be usable with E85. Even E10 is only approved by most for 2001 and up. It's cheaper, but fuel mileage takes a big hit. There are no motorcycles so equipped.

Anecdotally, E85 pump gas is said to actually test out to more like 30 to 50% ethanol.

I recall that a family member's new Camry about 1985, had an owner's manual warning about not using any fuel with ethanol or methanol in it. There was already a good bit of E5 appearing by then in the Northeast.
 
Heck I have run E85 8 gallons out of 17 in my Acura TL...

Ran just fine. Though the fuel trims were 12-15 percent positive vs the normal less than 7 percent positive.

E85 mixed with lower octane gas can really bump up octane decently. Even 4 gallons put in 10-12 gallons of 87 it makes a good difference.

I'm not saying to do this routinely or even do it at all. I did that just to run it. The fuel trims were interesting to note. They also came back dien to normal in a very short time after I ran 93 e10 back into the car.
 
Heck I have run E85 8 gallons out of 17 in my Acura TL...

Ran just fine. Though the fuel trims were 12-15 percent positive vs the normal less than 7 percent positive.

E85 mixed with lower octane gas can really bump up octane decently. Even 4 gallons put in 10-12 gallons of 87 it makes a good difference.

I'm not saying to do this routinely or even do it at all. I did that just to run it. The fuel trims were interesting to note. They also came back dien to normal in a very short time after I ran 93 e10 back into the car.
As a kid I had a friend who sometimes peed in the gas tank of his Yamaha 100 dirtbike. He swore it ran fine like that... Until it didn't! LOL
 
I've exclusively used zero ethanol fuel in everything with a carburetor(s) for the past 15 years. Also, for my home gasoline storage. I dose the tanks with Stabil 360 (used to be marine formula) for winter storage. The original Stabil would be fine for me not using ethanol, but that doesn't seem to be available anymore. All those rubber o-rings in a stored 4-carburetor motorcycle would a real party for ethanol.

Sadly, most all motorcycle petcocks have been vacuum operated for decades so you can't just run the carburetors dry. Unless you have one with a position feature that allows actual shutoff. An old BMW boxer bike I had for many years had glorious twin Karcoma manual petcocks. The carbs were extremely easy to access on each side as well. I can't remember how many times I took off down the road on that Beemer and realized a half mile later that I hadn't turned the petcocks on.
For sure you can run the carbs dry if they are vacuum operated.

If it has a petcock it's easy to access by nature. Disconnect the fuel line below the petcock, disconnect the vacuum source off the petcock or the intake boot, start the bike and run it dry. Unless you drain the float bowls which they are designed to do with a drain on the bottom. I haven't seen bikes, back to the 1970s and '80s, that don't have bowl drain plugs. It's a matter of wanting to put in the short amount of time to do it or not, possibly.

In any case good old red stabil goes in my tank as it may or may not get ridden for 4 to 8 weeks for any given stretch over the winter. Any Stabil formulation will work, IMO.

Ethanol is not the issue with gummed up carbs. My carbureted bike from 1980 that I recently sold never had an issue with E10, and e10 was never a consideration when those bikes were designed. I think it may have more to do with overall fuel system condition and keeping fuel lines/o-rings reasonably replaced at intervals. Honestly that was true back in the day, too. If a 20-40-year-old bike with 20-40-year-old fuel lines and rubber parts inside the carburetors has problems and it gets blamed on ethanol, that's not where the issue lies.

Also interesting article about the stability of higher octane gasoline with respect to being a more refined product. I see there could be some merit there.
 
For sure you can run the carbs dry if they are vacuum operated.

If it has a petcock it's easy to access by nature. Disconnect the fuel line below the petcock, disconnect the vacuum source off the petcock or the intake boot, start the bike and run it dry. Unless you drain the float bowls which they are designed to do with a drain on the bottom. I haven't seen bikes, back to the 1970s and '80s, that don't have bowl drain plugs. It's a matter of wanting to put in the short amount of time to do it or not, possibly.

In any case good old red stabil goes in my tank as it may or may not get ridden for 4 to 8 weeks for any given stretch over the winter. Any Stabil formulation will work, IMO.

Ethanol is not the issue with gummed up carbs. My carbureted bike from 1980 that I recently sold never had an issue with E10, and e10 was never a consideration when those bikes were designed. I think it may have more to do with overall fuel system condition and keeping fuel lines/o-rings reasonably replaced at intervals. Honestly that was true back in the day, too. If a 20-40-year-old bike with 20-40-year-old fuel lines and rubber parts inside the carburetors has problems and it gets blamed on ethanol, that's not where the issue lies.

Also interesting article about the stability of higher octane gasoline with respect to being a more refined product. I see there could be some merit there.
Yes, with minimal bother you could disconnect the fuel line and vacuum and run it dry. Draining the bowls would be a bit of work on a 4 carb UJM.
I may have been lucky, but I've never had a problem with usually leaving carb bowls full over 4 -5 months. Using E0 and Stabil in my case. Good advice on replacing fuel lines and carb bits every so often.
 
As the riding season is winding down for much of the Northern Hemisphere, I am looking for ways to keep my carborated Honda Shadow from needing a full carb clean next Spring.

E0 is not available anywhere near where I live. In the past I have used Stabil gas treatment and Seafoam, and I try and ride a mile or two every week or so, even if it's cold outside.

Last year I filled up with high octane at the beginning of Winter, with the idea that the gas might lose octane after sitting for a while, but I have no empirical evidence that this would be true.

Anyhow, I figure that BITOG is a good place to look for empirical evidence, or at least anecdotal evidence...

Thanks in advance!
20 years, not a single carb issue, all engines start on first/second pull every year, and bikes start instantly and run perfectly. My regiment?

91 octane (which has no ethanol here), add double does of Stabil, dose of MMO (or your fav petroleum distillate), and make sure all engine tanks are topped right up to remove as much air in the tank. All small engines run treated gas, all the time, not just when it's time to store. Bikes run treated gas for the last few rides.

That's it. No draining carbs, fogging cylinders, and any other insanity. Just park the engine, and it's ready to be started on demand when needed. For bikes I also attach a battery tender if it's going to be sitting for more than a month.
 
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