Number of weeks back I was reading in Wikipedia on plot holes in movies, one of the mentioned plot holes is in an awful movie I'm going to do my best to avoid: Battlefield Earth. But I digress. The plot hole, among others, is aviation fuel spoils after a few years, so it would be impossible to fuel aircraft on some stored for 1,000. My question is why does it spoil? Is it the kerosene that goes bad, or something else? If the kerosene, why does it go bad? Just a hydrocarbon, unless it's bombarded by UV light, I don't see why it should ever go bad. Nothing really eats it, yet, except perhaps some kind of GM bacterium.