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  #1  
Old 02-15-2011, 11:26 AM
N223JH N223JH is offline
 
Join Date: Apr 2008
Location: Boerne, TX
Posts: 228
Default Stale Autogas

While fueling my 12 yesterday, was approached by an RV10 builder who informed me that, "Car gas goes stale in two weeks and will eventually gum up those carburetors."

While I believe he is mistaken in the period of time required for the gas to go bad, it prompted me to query the group on collective knowledge. My experience with gasoline engines tells me that it takes more on the order of several months for varnish to appear in the carb's smaller passageways.

I'm flying 1x-3x a week now but I wonder if draining the tank and "running it dry" wouldn't be a bad idea for extended down-times.

Additionally, I do not recall if there was a specific prohibition regarding fuel stabilizer use in the Rotax paperwork (not at the hangar right now). Sta-Bile works well in chainsaw, lawnmower, etc-.

Thought maybe some of y'all might have some practical experience and/or authoritative reference bearing on these subjects.

Jim
RV12 #120264
flying 15 hours
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  #2  
Old 02-15-2011, 11:43 AM
mcems mcems is offline
 
Join Date: Apr 2008
Location: Salem SD
Posts: 163
Default

I have 300 gals of premium at a time delivered to my overhead tank ay my farm hangar and I treat the entire 300 gals with Stabil . I have had no problems doing it this way for years. I believe folks at Lockwood (Rotax center) recommended Stabil.


Brad stiefvater
Salem SD
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  #3  
Old 02-15-2011, 11:59 AM
allbee allbee is offline
 
Join Date: Aug 2006
Location: spokane, wa
Posts: 805
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I have the 912uls and I have gone a week without flying it. I use E10 all the time. If it goes a little longer I put in the pink stabil and still no problems. Sounds like you have nothing to worry about. I only fill my tank half way so I can put in fresh on a constant basis. hope this helps. Oh and make sure you buy your gas at a station that sells a bunch of fuel, that way you know it's fresh.
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  #4  
Old 02-15-2011, 12:47 PM
JBPILOT JBPILOT is offline
 
Join Date: Nov 2007
Location: Jesup, Iowa
Posts: 1,657
Default What I have done - -

Cold weather may slow down negative affects, but I have let a 912ULS sit for 2 months of cold weather, and didn't seem to make any difference. I think there would be many factors to consider. I wouldn't worry about it. Add some fresh if possible, and fly.

John Bender
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  #5  
Old 02-15-2011, 01:38 PM
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MartySantic MartySantic is offline
 
Join Date: Apr 2008
Location: Davenport, IA
Posts: 1,390
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Phil Lockwood at the IL Ultralight Safety Seminar last year, recommended Sta-Bil if the fuel sits in the plane's tank or storage tank longer than 1 month.
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  #6  
Old 02-15-2011, 03:27 PM
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mculver mculver is offline
 
Join Date: Dec 2008
Location: Redmond, WA
Posts: 269
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If there were a risk of car gas going stale because every last drop isn't used up, there'd be at least a couple of dead cars out there...
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  #7  
Old 02-15-2011, 03:37 PM
JBPILOT JBPILOT is offline
 
Join Date: Nov 2007
Location: Jesup, Iowa
Posts: 1,657
Default Another story - only of interest - -

I bought a 1 year old 'builder' car 5 - 6 years ago. Decided not to finish it then. Left it sit for 4 1/2 years ( inside), then decided to finish it. Put a battery in it, and it started instantly, and run like it had been fueled the day before. I know cars can compensate for many ills, but as I said, an interesting story.

John Bender
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  #8  
Old 02-15-2011, 04:35 PM
Daver Daver is offline
 
Join Date: Nov 2006
Location: Albuquerque
Posts: 297
Default bad gas

I've heard this "gas goes stale" stuff for years but I've never seen it.

I've had yard equipment with 2-4 yr old gas in it that ran fine - never a problem.

How do these rumors get started?

Dave
-9A flying (out of ph 1 testing)
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  #9  
Old 02-15-2011, 06:28 PM
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AlexPeterson AlexPeterson is offline
 
Join Date: Sep 2005
Location: Maple Grove, MN
Posts: 2,333
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I think the problem is not so much the fuel goes stale, but when a significant portion can evaporate, the stuff remaining looks and smells like varnish. This is particularly a problem on carbureted engines. Fuel evaporates from the carb, and the float valve opens, replenishing the evaporated gas. Eventually the goo in there becomes essentially "condensed" gas. For carb'd engines that are stored, some sort of a fuel shut off valve is important to prevent this. Additionally, the fuel may be undergoing some sort of chemical reaction in the presence of air, I don't know.

If I had to guess, I'd think Sta-Bil might work simply by forming a skin on the gas? It smells a lot like diesel fuel...
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  #10  
Old 02-15-2011, 06:43 PM
Danny7 Danny7 is offline
 
Join Date: May 2008
Location: central oregon
Posts: 1,089
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I had gas go bad after 6 months or so in the lawn mower. it barely ran and produced a lot of white smoke. I believe it was an eth/ gas blend, and the last time i ran eth in any of my small engines
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