Av gas & reg gas
 

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.

Re: Av gas & reg gas
 

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/

Re: Av gas & reg gas
 

Just what do you mean by "quality of the gas" and for what purpose and what end result?

Re: Av gas & reg gas
 

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

Re: Av gas & reg gas
 

AVGAS is one component of the gasoline pool. For those refineries that don't sell it as AVGAS it is blended to Super Unleaded.

Re: Av gas & reg gas
 

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.

Re: Av gas & reg gas
 

"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.

Re: Av gas & reg gas
 

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

Re: Av gas & reg gas
 

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.

Re: Av gas & reg gas
 

I do all my yard machinery that way too. I got tired of replacing expensive plastic carburetors that were plugged up with crud.

Re: Av gas & reg gas
 

Is aviation gas less prone to becoming stale? Or is that an old wives tale?

Re: Av gas & reg gas
 

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.

Re: Av gas & reg gas
 

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.

Re: Av gas & reg gas
 

Would that indicate products such as Sta-Bil might be overkill and no longer necessary over winter storage?

Re: Av gas & reg gas
 

"The problem now is ethanol separating out due to moisture."
Thought that this part of the statement sorta' covered that.

Re: Av gas & reg gas
 

Might be true but nothing wrong asking the question--Is there? I would wager there may be some differing opinions--

Re: Av gas & reg gas
 

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

Re: Av gas & reg gas
 

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.

Re: Av gas & reg gas
 

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.

Re: Av gas & reg gas
 

One of the assets of avgas is the lower water content from gasoline.

Re: Av gas & reg gas
 

I would think the vapor pressure differences would be a real concern with automotive fuel in aviation use!

Re: Av gas & reg gas
 

There is no water content in gasolin3. It all settles to the bottom of the tank. That is why every preflight includes draining the sump of each tank into a clear glass container and checking for water.

Re: Av gas & reg gas
 

I totally agree with your comments. Here in NJ we have had 10 % for years. I use it all my old cars for over 20 years or when ever it came out.. Never had a fuel related problem - pumps, carbs, etc. The gas in put in October/November is the same that starts the car in April with no problem. no junk like sta-bil either. My son used sta-bil one year and it totally gummed up his carb

Re: Av gas & reg gas
 

As far as I'm concerned, it is overkill. Never used it and never had a problem with 10 % in cars that sat over the winter.

Re: Av gas & reg gas
 

I have and continue to use 10% ethanol in all my small engines and modern cars.

I do use an emzine-based additive to neutralize the alcohol in my flathead gas just to protect the steel tank from corrosion. The rest of the fuel system in it has been rebuilt to avoid ethanol problems.

Re: Av gas & reg gas
 

Guess it just depends on your experiences with the stuff. I have seen a lot of damage from the ethanol, it eats up aluminum, rubber, steel, etc. If you can get by using it, guess that is a good thing, but not my experience. Non-ethanol gas is easy to come by where I live so problem solved (for me).

Re: Av gas & reg gas
 

I agree with JSeery. The few extra bucks each year for me is not worth the chance. I use non-ethanol in everything I have that has a carb.

Re: Av gas & reg gas
 

For years folks would purchase a pint of an alcohol product to absorb the condensate water that forms in the fuel tank over the summer months and tends to freeze up during the winter causing problems. This was long before they actually started adding it to fuel. Now that they add it in there on a regular basis, it shows up another problem with alcohol. When it absorbs water, it will get saturated and fall to the bottom of the tank where is starts growing fungus and picking up other trace materials in the fuel that can come from long term storage. The volatile compounds in fuel tend to evaporate and leaves the chemical structure changed as further oxidation occurs. The mix of all this is what corrodes metals & deteriorates rubber compounds and it takes a while for it to clear the system since most fuel tanks have a bit of a stand pipe in the bottom. Most tanks are vented and fuel likes to be sealed up away from air to keep it from oxidation.


A similar thing can happen in the float bowl of the carburetor or in fuel pumps if the vehicle sets for long periods. This can be reduced a lot by daily use of the vehicle and a constant renewal of fuel in the tank but this isn't always practical. Draining the tank and fuel system is not all that practical either unless the car is going to set for extended periods but I doubt if it's common for folks to do this. Sea Foam, Sta-Bil, and other fuel stabilizer additives might slow the oxidation process some but it won't completely stop it or evaporation. Your engine has to burn that stuff too right along with everything else.


Colder times of the year generally have less condensation unless the vehicle is subjected to more extreme changes in temperature from cold to warm & warm to cold. Evaporation is slower in colder months so that can be a good thing for fuel. Humidity drops a lot during the cold months so that helps too. When I worked in the Rockies, we would get a rapid warm up coming up from Arizona at times during the winter months. We would be having vapor lock problems with the fuel trucks till a cold front would come through again. The winter fuel with it's higher volatility would vapor lock easily if it gets too warm.

Re: Av gas & reg gas
 

Agree Rotorwrench ethanol in fuel is detrimental to small engines and old engines anything carburated. We need to explore for more oil (it's here) and bury more politicians.

Re: Av gas & reg gas
 

Sorry that message was from me. Didn't realize Seth was logged in on this computer.

Re: Av gas & reg gas
 

This is Mike Jr... posting on dad's old account. I get on here every few months to keep up on old messages, etc... look through his old messages for info on his old cars I still have, and sometimes browse though the forums.

Anyway, as was said, gasoline has a certain average volatility... which is how easily it evaporates. Gasoline is also a mixture. It's a mixture of lights and heavies... components that evaporate easily, and not so easily. Auto fuel has a fairly wide range... especially nowadays, since the higher pressure EFI fuel systems (in tank pump) of today's cars are not prone to vapor lock. This allows their fuel to have a wide range of lights and heavies, and still maintain the correct 'average'.

Aviation fuel does NOT have this luxury. It cannot have as many 'lights' as automotive fuel, as vapor lock is a HUGE issue in an airplane. Vapor lock is further aggravated by the lower air pressure of altitude. To have the proper AVERAGE volatility, it has to have a tighter blend of components... fewer lights, fewer heavies, and more in the middle.

Gasoline goes stale by the lights evaporating off. Since Av-Gas has fewer 'lights', or easily evaporating components, it has a longer shelf life, and does not go stale as easily as automotive fuel. Its longer shelf life, along with the fact that it has no ethanol, makes it PERFECT for small engines, and applications like our cars, that are only operated infrequently, and are stored for periods of time. Sure, these items do not need the extra octane, and if you have non-ethanol fuel nearby, that's fine... but, Av-Gas is the best... as it has an incredible shelf life, as well as no ethanol.

Fuel goes 'stale' by the lights evaporating out... so to maximize shelf life, store the vehicle in a cool place. Store it with a full tank, so the lights have less head/air space above the fuel to evaporate into... and if you're storing the fuel in containers, store them in SEALED units, filled to the top if possible, so the lights cannot evaporate out. Out of the sunlight is also good.

Good Luck

Re: Av gas & reg gas
 

Doesn't matter I feel the same way.:)

Re: Av gas & reg gas
 

Consider yourself lucky. 10% ethanol blend has destroyed the carburetors in 4 of our Stihl chainsaws/leaf blowers/string trimmers. It's caused us significant headaches in all carbureted 4 cycle engines also.

Re: Av gas & reg gas
 

I do consider myself lucky,Seth, having survived for 86 years eating, drinking and breathing all kinds of BAD foods, liquids and air warned about by EPA, OSHA and well meaning organization plus others. I will keep on and maybe my vehicles and I lill make it another couple of years.

Re: Av gas & reg gas
 

An old time marine mechanic told me he has been using AV gas in all his small equipment including 2cyl outboards He say he can leave it in the tank and carb with no ill effects like you would get from gas with alcohol in it. Another friend said he ran 30% 102 octane AV gas and 70% regular gas in his vintage midget and said the car ran better and he had much quicker lap times. Thank you for all your thoughts. We live in Massachusetts, and there no such thing as alcohol free gas here. I used to run Amoco Ultimate, that all went away.

Re: Av gas & reg gas
 

I tied in an outboard once and I could not get the damn thing to fire. Think the fuel was just to lazy.

Re: Av gas & reg gas
 

Funny we put 10% Eth in our now $40-50g trucks. They run fine. But they are made for it... I guess. Norm is to buy a new vehicle every 10 yrs sooo... Maybe that's all they are made for.



Here there is non-eth available. called Non-Oxygenated. I'll continue to buy this for boat motors, lawn mowers. trimmers, and my fords that may sit for long periods. No issues.



If you are going to burn a tank on a trip in a few days, eth isn't going to do "huge" damage if anything in my experience.


I'm waiting on my nuclear powered lawn mower as promised in the 50's :).

Re: Av gas & reg gas
 

I'm a naturalist, so I'm with ya but... All that LP they tapped in the bush yrs on public land, will be going to the EU now. We will see very little.


That land was setup as a national treasure for everyone in American. Sure it's complicated. But it's really like a savings account or a place we can just enjoy.


Kinda wish we could make solar and electric cars work, then there would be more gas available. or not... my 2 cents.

Re: Av gas & reg gas
 

And that statement is 100% wrong!
The only difference in small equipment is, over a long period of time it may, but not likely, lead foul the spark plug.
As noted before, the old av gas, before 100LL, would store for a LONG time without going bad, even for racing. The 100LL of today WILL store and stay good longer than regular street gas if corked up and kept cool.
I have been running av gas for racing since the early 50's. In vintage racing of today, it is still a bargain over "race gas". In any automotive engine, you need to know how to tune for it though. It will generally need 4 to 5 degrees more advance on the timing and slightly richer on the mixture. The plugs will appear gray from the lead so don't let that send you astray. Read the center electrode only.
At the end of racing season, I have always run what is left in the barrel out in my chain saws , weed trimmers and parts chaser.