"Over time, Mogas deteriorates faster than Avgas"

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"

"Jay Honeck" wrote

I have never noticed the slightest difference. Now, of course, I
don't let my plane sit for months, or even weeks -- but my motorcycle,
convertible, lawn mower(s), lawn blower(s) and vacuum, and snow
blower(s) ALL sit for many months, unused. No problemo starting or
running in the spring/winter.

Also, we have a shell petro-chemical engineer in our circle and he tells
us that the aromatics in mogas evaporate more readily thuus causing the
degradation in quality.

Again, a cite? ANYTHING in writing, ANYWHERE about this problem with
mogas?

You must use your stuff deep enough into the season, and fire it up early
enough in the season to avoid any problems.

There have been too many people say that they have had problems with their
small engines to discount it.'

Add me to the list. I recently got out my 6 1/2 HP Briggs overhead valve
push mower, and it would not start when I put fresh gas in.

I took the carb apart, and it is complete trash. I don't even think
cleaning it would help. It will require a new carb.

It has been about 1 1/2 years since I last used it. It is JUNK , now.

Would av gas be any better? I don't know. I do believe that you had better
keep mogas less than a year in your machines, though.
--
Jim in NC

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"

Morgans wrote:

Add me to the list. I recently got out my 6 1/2 HP Briggs overhead valve
push mower, and it would not start when I put fresh gas in.

I took the carb apart, and it is complete trash. I don't even think
cleaning it would help. It will require a new carb.

It has been about 1 1/2 years since I last used it. It is JUNK , now.

Would av gas be any better? I don't know. I do believe that you had better
keep mogas less than a year in your machines, though.

I've never had problems letting gas sit through one winter (about 5-6
months where I live), but I now use Stabil just to be on the safe side.
I had a Kawasaki KH400 that I let sit for 1.5 years once. That was a
HUGE mistake. The bike wouldn't start so I pulled the three carbs. The
float bowls were covered with a green slime that looked like algae.

I did some resarch at the time and learned that certain things actually
do live and grow in gasoline. I was finally able to clean the carbs
enough to get them working, but it took many hours of mechanical
scrubbing and poking open of fine orifices in the carbs. The green
slime was completely immune to carb cleaners, alcohol, acetone, etc. I
tried every common solvent and cleaner I had and nothing would touch
whatever that stuff was.

Matt

"Matt Whiting" wrote in message ...

I did some resarch at the time and learned that certain things actually do live and grow in gasoline. I was finally
able to clean the carbs enough to get them working, but it took many hours of mechanical scrubbing and poking open of
fine orifices in the carbs. The green slime was completely immune to carb cleaners, alcohol, acetone, etc. I tried
every common solvent and cleaner I had and nothing would touch whatever that stuff was.

Matt

Did you try soap and water?

Blueskies wrote:
"Matt Whiting" wrote in message ...
I did some resarch at the time and learned that certain things actually do live and grow in gasoline. I was finally
able to clean the carbs enough to get them working, but it took many hours of mechanical scrubbing and poking open of
fine orifices in the carbs. The green slime was completely immune to carb cleaners, alcohol, acetone, etc. I tried
every common solvent and cleaner I had and nothing would touch whatever that stuff was.

Matt

Did you try soap and water?



Yep. And Pine Sol. And bleach. And...

Matt

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

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

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