Av gas & reg gas

R

russcc

Well-known member
Although Av Gas is fairly expensive, there is an airport right handy that I can get it from. I will be using it in my small equipment like chain saws, generators, mowers etc. How does Av gas mix with regular gas, as I would like to boost the quality of the gas I run in the roadster and '40 coupe.
Thank you Fordbarners.
 
I think the whole idea of AV gas is to not have ethanol in you fuel, mixing it with pump gas kinda defeats the purpose. I think there is a web site that lists ethanol free stations. I am lucky to have 2 ethanol free stations within about a mile from me.

Found the link

https://www.pure-gas.org/
 
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If I remember from my ancient propeller driven aircraft days, Aviation Gasoline (AVGAS) is regular gasoline with a higher "octane" rating. It used to come in three grades with the highest grades being 100-110 and 115-145. The purpose of the increased octane was to help prevent "detonation" under the increased compression ratios of higher performance engines.
Mixing it with regular gas would just defeat the purpose for which it was designed.
If you're purchasing it for use in small engines to avoid the perils of alcohol flavored fuels, you are paying a large premium when there are less expensive means to achieve the same end.
dw
 
AVGAS is one component of the gasoline pool. For those refineries that don't sell it as AVGAS it is blended to Super Unleaded.
 
Aviation fuel used to be available in three different octane ratings but that has been reduced to one for the last 40 years. 100 LL or low lead still has a lot of tetra ethyl lead or TEL in it but less than what the old 100/130 fuel used to have. I wouldn't recommend running leaded gas in any two stroke engines since the unburned lead deposits can actually be harmful to all the components related to the combustion chamber. For low compression engines, it will leave a lot of deposits in them as well but the worst that can happen is the plugs will get fowled with the stuff and there will be a build up of the deposits in the combustion chamber at times depending on how the vehicle is operated. Aircraft engines are mostly air cooled with big 4 7/8" or larger pistons and they need the lead to cushion the large valves that they have. We're talkin 360 CID 4-cylinder and 540 CID 6-cylinder engines here. They couldn't be much more different than car engines.


There are regulations on storage of avgas to insure that it doesn't get contaminated with water or other types of fuel. The quality of the components are also regulated. You can't have highly volatile fuel if you want to control vapor pressure so as not to have any possibility of vapor lock at altitude. Mogas has no such regulations and it's volatility changes from summer to winter. They add alcohol and other additives depending on government regulatory concerns and contractual agreements with the retailer companies.


Just look for a retailer that doesn't have alcohol added to their mogas. This should be fine for our old car's fuel systems. 100LL is for aircraft and that's why it's so expensive. Super unlead mogas with no alcohol would be just as good for an automobile engine.
 
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"Mogas has no such regulations and it's volatility changes from summer to winter" EPA mandates the vapor pressure of gasoline. In summer it is quite lower than it used to be somewhere around 6psi vs 10psi which means no butanes in the summer. In winter with cold weather it has to be higher like 15psi with butanes so the gasoline will vaporize in the cylinders. The colder the region the higher the vapor pressure required.
 
Here in "Corn Country" we can still buy Amoco/BP Ultimate, the premium line. It doesn't have alcohol in it. Might be different in your area
 
Whenever I store my yard equipment for any period of time.I dump the mixed gas (unleaded and 2 stroke oil) back into the can, start and idle the tool on what's left of the gas in the carburetor until it dies. Then I remove the gas cap and cover the fill hole with a fine screen to keep the bugs out.Any residue evaporates through the screen.
 
I do all my yard machinery that way too. I got tired of replacing expensive plastic carburetors that were plugged up with crud.
 
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34fordy said:
Is aviation gas less prone to becoming stale? Or is that an old wives tale?
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Old wives tale now. All gasoline components are hydrotreated to get rid of sulfur to 50ppm or less. That also converts the unstable cracked part of gasoline to something more stable. The problem now is ethanol separating out due to moisture.
 
I think this "Alcohol gas problem" is way over stated. I have used the 10% Alcohol gas since it came out with no problems in my Flathead V8, Cessna 85, 100, 145, Lycoming 150 Hp, numerous tractors, lawn mowers, chain saws and smaller engines with no problems. My only problem was when lead was removed I was suckered into using some of the "Insted of Lead " product that a while jelled up in the float chamber carbs. I have many times allowed alcohol gas to remain for over a year and had no problem. Beats me why I am so lucky.
 
mrtexas said:
Old wives tale now. All gasoline components are hydrotreated to get rid of sulfur to 50ppm or less. That also converts the unstable cracked part of gasoline to something more stable. The problem now is ethanol separating out due to moisture.
Click to expand...

Would that indicate products such as Sta-Bil might be overkill and no longer necessary over winter storage?
 
51 MERC-CT said:
"The problem now is ethanol separating out due to moisture."
Thought that this part of the statement sorta' covered that.
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Might be true but nothing wrong asking the question--Is there? I would wager there may be some differing opinions--
 
I keep a storage tank of non ethanol gas treated with Stabil on my farm. I use it for small engines and as an emergency supply. I think strait gas lasts longer than e10. We keep it 2 years and then use what is left.

That being said, when we travel in our old Fords we often only see one gas station in a town. Looking for non ethanol is impossible. I have never had a problem with ethanol in my cars.

John
 
34fordy said:
Would that indicate products such as Sta-Bil might be overkill and no longer necessary over winter storage?
Click to expand...

Remember how gasoline used to be yellow colored? That was from the cracked unstable components. The unstable components are treated to reduce sulfur and gasoline is now water clear. I believe Sta-Bil is to keep the ethanol from dropping out due to moisture. I'd say it is necessary for winter storage IMHO. Although I don't use it.
 
If anyone recommends Mogas in an airplane then they need to be careful. That makes a person liable in a court of law. No matter what you think is OK in an airplane, you need to keep it to yourself if it isn't AVGAS or zero alcohol fuel used in STC requirements and under strict directions. No alcohol related fuels are used in the STCs. A person also needs to be aware of the engine manufacturers service bulletins on the subject.

If you open your fuel tank and smell turpentine then it has already turned.
 
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