"Over time, Mogas deteriorates faster than Avgas"

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

On Sat, 15 Sep 2007 13:45:13 -0700, Jay Honeck
wrote:

This from a thread in rec.aviation.owning:

Leave unleaded mogas in your lawnmower for a year, and it
likely won't start. Autogas lacks the stabilizer package found in
avgas.

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?

in australia at least there are additives in automotive fuel that
degrade on exposure to uv light. this causes a fine flakey sediment to
settle out. this was the cause of 'dont use in aircraft' warnings in
our country.

Stealth Pilot

in australia at least there are additives in automotive fuel that
degrade on exposure to uv light. this causes a fine flakey sediment to
settle out. this was the cause of 'dont use in aircraft' warnings in
our country.

They *added* stuff to the gas that causes flakey sediment?

Have you got a cite for that?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On Sun, 16 Sep 2007 21:14:12 +0800, Stealth Pilot
wrote:

in australia at least there are additives in automotive fuel that
degrade on exposure to uv light.

A lot of transparent fuel tanks in Oz, are there? :-)

Ron Wanttaja

Again from Chevron
http://www.chevron.com/products/prod...esting/pg5.asp
sites the internationally recognized formulation standards which include
specs for stability and gum solvent content.

We own two 10k gal gasoline tanks, one for 89 oct unleaded and one for 89
oct unleaded plus lube additive for the old truck valve trains. Each of
those tanks sit less than 1/2 full for 5-6 months before I buy a load to
split between them, usually in the spring. When less than 1/2 full, those
tanks have a lot of surface area exposed allowing evaporation of the gas's
lightest components, not to mention water condensation. We see no problems
with gasoline that has been stored for 5-6 months. We've got a fleet of
over 50 gas powered trucks ranging from pickups to midsized bulk trucks that
range in age from the 1960's to current production. The trucks that don't
get used year around start and run fine each spring with the fuel that's
left in the tanks from when we put them away each fall. No fouled plugs,
not fuel system problems.

Our fuel rep said that you "might" see some performance degradation in high
compression/high horsepower engines from the fuel oxidizing slightly while
it sat, but as long as it meets the current manufacturing standards, it
should be fine. He said that most problems reported are from users that
have contaminated gas that has all but totally evaporated in their fuel
systems. The contaminates remain behind then get flushed into carb jets and
needle valves or fuel injectors by fuel from the tank. He said that
contamination is a much bigger problem than age.

We buy unbranded fuel strictly on price. Sometimes it contains ethanol,
sometimes it doesn't, sometimes we end up with a branded product, most of
the time we don't. We never notice a difference. Our guy wasn't pushing
any special brand or formulation. YMMV.

I noted that several of the posts mentioned small engines. Are these 4
strokes burning straight gas or 2 strokes burning blended gas/oil mixtures?

Jim



"Jay Honeck" wrote in message
ps.com...
This from a thread in rec.aviation.owning:

Leave unleaded mogas in your lawnmower for a year, and it
likely won't start. Autogas lacks the stabilizer package found in
avgas.

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?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

I noted that several of the posts mentioned small engines. Are these 4
strokes burning straight gas or 2 strokes burning blended gas/oil mixtures?

In my case, it's both. I've got an annoying mix of 2- and 4-stroke
gasoline tools -- but none of them show any kind of problems running
"old" gasoline.

Thanks for the information about your experiences. I'm sure gasoline
EVENTUALLY goes "bad", due to evaporation and water contamination --
but I think it's highly unlikely that "aviation gasoline" is any
different than "auto gasoline" in this regard.

I simply don't believe that the oil companies put any extra money into
production of aviation gasoline, especially when they sell such a
tiny, insignificant amount of it. Does anyone (besides me) think that
oil companies would keep the two formulas as close to identical as
possible, with the exception of lead, in the interest of cost
savings?

Personally, I think this is just another busted aviation myth. But
I'm sure there will always be those who believe that the $4.40/gallon
stuff is better than the $2.89/gallon stuff, just like there are those
who swear by Marvel Mystery Oil, flying on "the step", and fear
stalling when turning the same direction as the wind.

(Hey -- anyone want to debate "shock cooling" now that it's getting
cold out?)

:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

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.

Jim

"Jay Honeck" wrote in message
ups.com...
I noted that several of the posts mentioned small engines. Are these 4
strokes burning straight gas or 2 strokes burning blended gas/oil
mixtures?

In my case, it's both. I've got an annoying mix of 2- and 4-stroke
gasoline tools -- but none of them show any kind of problems running
"old" gasoline.

Thanks for the information about your experiences. I'm sure gasoline
EVENTUALLY goes "bad", due to evaporation and water contamination --
but I think it's highly unlikely that "aviation gasoline" is any
different than "auto gasoline" in this regard.

I simply don't believe that the oil companies put any extra money into
production of aviation gasoline, especially when they sell such a
tiny, insignificant amount of it. Does anyone (besides me) think that
oil companies would keep the two formulas as close to identical as
possible, with the exception of lead, in the interest of cost
savings?

Personally, I think this is just another busted aviation myth. But
I'm sure there will always be those who believe that the $4.40/gallon
stuff is better than the $2.89/gallon stuff, just like there are those
who swear by Marvel Mystery Oil, flying on "the step", and fear
stalling when turning the same direction as the wind.

(Hey -- anyone want to debate "shock cooling" now that it's getting
cold out?)

:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On Sep 16, 3:09 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.

They do the same here. The truck's tanks have to be flushed
with 100LL before they can fill them with it and the batch is tested
and a detailed printout sent with the load. The liability for Avgas is
huge compared to Mogas, and the refinery and trucking outfit have to
carry more insurance for that, too. There are many ways we pay for our
litigious society.

Dan

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.

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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