"Over time, Mogas deteriorates faster than Avgas"

On Sep 16, 2:09 pm, "Jim Burns" wrote:
The biggest difference between standard mogas and avgas would be that avgas
is actually manufactured to a tighter Mil spec than the petroleum industry
standard for mogas. It's also handled in ways to minimize contamination.
Mogas can be transported in the same pipline or truck directly after a load
of diesel or other fuel without any cleaning procedure. Mogas and diesel
fuel can be co-mingled in the same truck, in separate compartments. Avgas
must be handled and hauled alone. Avgas can only follow mogas or after
cleaning procedures. Same for Jet A, Jet A can follow a Kerosene shipment,
but not a diesel fuel or gasoline shipment.


Avgas is not transported by pipelines in the U.S. due to the existence
of TEL contaminating pipeline. They're all trucked, often from a
refinery half the country away. That's one of the big reasons why
100LL costs more than $1/gallon over mogas, and that price delta is
going to further increase as the overall consumption avgas decreases.

As a fellow mogas flyer who burn over a thousand gallon of mogas a
year in my plane, and believing the aviation industry is stupid not
moving away from engines requiring 100LL (they should only install
gasoline engines requiring 91/96 or lower octane, or aero diesel
engines into new production planes, if you ask me), I do believe that
mogas deteriorates faster than avgas. The reason is probably due to
different chemical make-up btween mogas and avgas. Mogas's end
distillate is slightly heavier, meaning it has more larger hydrocarbon
molecules in the mix compared to avgas. It also contains a higher
percentage of aromatics hydrocarbon. Those chemical property of
mogas, when oxidized over a long period of time, tend to make the fuel
off-spec more quickly than 100LL.

http://www.generalaviationnews.com/e...olumn&-nothing

Look at the brighter side Jay. If we're paying $1.50/gal less in
fuel, a good chunk of our flying is free. We should simply go fly
more often.


On Sep 15, 1:45 pm, Jay Honeck wrote:

You know, I've heard that ever since I started using mogas in my
planes, but I've never seen a cite, nor have I *ever* noticed a
problem with unleaded gasoline in *any* of my lawn mowers, leaf
blowers, or snow blowers.

I put 'em away in the spring/winter, and start 'em up the following
winter/summer -- and away we go. Same with my Honda Goldwing -- I
top
it off, and it just sits till next year. No troubles.

Can anyone point me to anything that proves (or disproves) the "fact"
that unleaded mogas deteriorates faster than avgas?

Jim Burns wrote:

It's also handled in ways to minimize contamination.

I always thought the special handling was because of the lead in 100LL and
for the protection of the unleaded fuels from lead contamination, not for
the protection of the Avgas.

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On Sep 15, 8:40 pm, "Maxwell" wrote:
"Robert M. Gary" wrote in glegroups.com...



It depends where you live. Out here in California they put corn or
whatnot in the autogas. If you leave that stuff in your mower or weed
eater for even 30 days you'll spend the next 30 days in the shop. I've
had my current weed eater in the shop 3 times this year just to clear
out the carb due to the crappy gas. The shops recommend always running
then dry and never, ever, storing gas for me than 30 days. Even at
that you need to have the lines cleaned to remove the sludge that the
mogas creates.

Have you tried 100LL, or racing fuel from a local speed shop? We use so
little in weed eaters and such, it might be worth the price.

I have but I'm concerned that the lead and high octane might create
deposits in the engine. What I need is not better gas but just clean
(even crappier) gas.

-Robert

On Sep 16, 11:16 pm, M wrote:
As a fellow mogas flyer who burn over a thousand gallon of mogas a
year in my plane, and believing the aviation industry is stupid not
moving away from engines requiring 100LL (they should only install
gasoline engines requiring 91/96 or lower octane, or aero diesel
engines into new production planes, if you ask me), I do believe that
mogas deteriorates faster than avgas. The reason is probably due to
different chemical make-up btween mogas and avgas. Mogas's end
distillate is slightly heavier, meaning it has more larger hydrocarbon
molecules in the mix compared to avgas. It also contains a higher
percentage of aromatics hydrocarbon. Those chemical property of
mogas, when oxidized over a long period of time, tend to make the fuel
off-spec more quickly than 100LL.

http://www.generalaviationnews.com/e...ail.lasso?-tok...

Look at the brighter side Jay. If we're paying $1.50/gal less in
fuel, a good chunk of our flying is free. We should simply go fly
more often.

On Sep 15, 1:45 pm, Jay Honeck wrote:





You know, I've heard that ever since I started using mogas in my
planes, but I've never seen a cite, nor have I *ever* noticed a
problem with unleaded gasoline in *any* of my lawn mowers, leaf
blowers, or snow blowers.

I put 'em away in the spring/winter, and start 'em up the following
winter/summer -- and away we go. Same with my Honda Goldwing -- I
top
it off, and it just sits till next year. No troubles.

Can anyone point me to anything that proves (or disproves) the "fact"
that unleaded mogas deteriorates faster than avgas?- Hide quoted text -

But is there any real future in mogas for aircraft. Its getting pretty
hard to find FAA legal mogas. Out here in California almost all mogas
is prohibited by the STC's.

-Robert

Robert M. Gary wrote:

But is there any real future in mogas for aircraft. Its getting pretty
hard to find FAA legal mogas. Out here in California almost all mogas
is prohibited by the STC's.

-Robert

I spent some time with a friend that is fairly high up the corporate latter
of one of the top 15 oil companies this weekend and we were discussing just
this. He said in the states that do not require marking of gas with or
without ethanol, Arkansas being one of them. That the chance of you buying
gas without ethanol over the long run is pretty much zero. Even in those
states that do have marking requirements the chances of getting a batch that
has it even in an unmarked pump are going to be pretty good.

The hell of it is, Robert, that the mogas is perfectly legal until they dump
it in the delivery trailer along with the prescribed amount of ethanol. The
refinery will sell you all the legal mogas you want so long as you can take
8000 gallon loads.

Jim

--
"If you think you can, or think you can't, you're right."
--Henry Ford



hard to find FAA legal mogas. Out here in California almost all mogas
is prohibited by the STC's.

-Robert

On Mon, 17 Sep 2007 06:16:42 -0000, M wrote:


...I do believe that
mogas deteriorates faster than avgas. The reason is probably due to
different chemical make-up btween mogas and avgas. Mogas's end
distillate is slightly heavier, meaning it has more larger hydrocarbon
molecules in the mix compared to avgas...

My understanding is that the vapor pressure of avgas is lower than
mogas, to prevent vapor lock at high altitudes. This would make it
keep longer if the storage container isn't perfectly sealed, as mogas
would lose more of the volatile fractions. It would also explain why
avgas plain smells better.

For 2-stroke flyers, there are also concerns about the longevity of
premixed fuel/oil (another endless topic on the ultralight boards).

-Dana
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On Mon, 17 Sep 2007 10:53:08 -0700, "Robert M. Gary"
wrote:

Have you tried 100LL, or racing fuel from a local speed shop? We use so
little in weed eaters and such, it might be worth the price.

I have but I'm concerned that the lead and high octane might create
deposits in the engine. What I need is not better gas but just clean
(even crappier) gas.

The local airport (7B3 Hampton NH) sells mogas bought from the
terminal in Portland ME that has no additivates whatever. I buy it
($3.90 a gallon) for the small engines (chain saw, generator,
off-season lawnmower and snow blower) that are likely to sit for
months between uses.

Blue skies! -- Dan Ford

Claire Chennault and His American Volunteers, 1941-1942
new from HarperCollins www.FlyingTigersBook.com

"Matt Whiting" wrote in message ...
Jim Logajan wrote:
Matt Whiting wrote:
The float bowls were covered with a green slime that looked like
algae.

Interesting. A web search suggests it could have been algae, but the web site below (among others that have similar
text) claims what you dealt with was (probably) a formation of wax and asphalt. I can see how the latter two would be
a pain to clean out! Did you try anything like the product known as "Goo Gone"?

http://dieselfueldoctor.com/fuel_solutions.html

No, I was not familiar with Goo Gone then (this occurred in about 1980). Yes, I think this was more than simple algae,
but I know it was the most tenacious coating I've ever seen on aluminum!

Matt

Maybe "simple green" would take it off.... ;-)