"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"