ORIGINAL: Bobhend
That's the problem question with everything. Our Whirlpool fridge is still running after 22 years with no problems. A new replacement Whirlpool is all new technolgy, new factory etc. and designed for maximum effeciency with little regard for lasting 22 years.
On fuel, I ran into serious problems with old 4S and 2S fuels that went bad, probably due to water absorption. The fuels had sat around too long due to a slow season last year. I believe water got in due to sitting with a pump mounted on the jug, and due to pumping unused fuel back into the jug [it gets water due to the exhaust pressure]. I am going to use more of these 2 quart jugs
http://www3.towerhobbies.com/cgi-bin...?&I=LXJ810&P=7 and I found a handy pour spout at Walmart auto section for $.50 because pouring fuel out of a jug always dribbles down the side of the 1 gal jug.. I am going to store any fuel pumped out of tanks in a ''USED'' jug. I spent a ridiculous amount of time tuning engines and changing glow plugs before I figured out the fuel was bad. In addition to start and tuning difficulties, the engines would suddenly quit mid-flight . Problems with about 7 engines cleared up when I started using new fuel and re-capping the jug every day.
I keep my hose plugged back into the vent line on my filler cap when not in use. It is essentially a sealed loop. I leave my Hobbico Top Fueler MK II connected & I pump unused fuel back into the jug.
When I resurected all my equipment after the 14 year hiatus I had 1 gallon of 15% Cool Power that was unopened & just a little over 1/2 gallon in the jug on my flight box that had been left in the closed loop as descibed above. Both were kept indoors in a semi climate controled condition out of direct sunlight.
The unopened jug was just fine & I used it as my initial fuel for starting up my engines, 2 of them NIB that I had purchased just before I was lead away from the hobby. A Saito FA150 on spark ignition & a glow ignition FA180. I also had a glow ignition FA91S that had low hours that I also started on the 14 year old unopened fuel.
The fuel that was left sealed after use had some fine white sediment floating in the bottom. I filtered it through a coffee filter & gave it a try. To my amazement it peformed just about like the unopened gallon W/perhaps a little more roughness @ idle in the glow ignition engines.
There was no appreciable difference in performance when I purchased a case of new 15% Cool Power fuel. Bear in mind that this was used purely for test stand runs so I was not gambling on destroying any aircraft by utilizing old fuel.
Conclusion? If kept sealed from atmospheric moisture & kept out of direct sunlight in a climate controled inviornment, glow fuel has a long shelf life. Even after opening, if care is taken to keep the jug sealed, there is little degredation.
Just my personal experience. YMMV. I do not run any 2-stroke engines, all 4-stroke Saitos. There may or may not be any difference when 2-stroke engines are involved as far as pumping contaminated fuel back into the jug when draining the tank.