I recently pulled out of storage my old Coleman 2-burner stove (with the old red fuel tank). Though I don;t use it anymore because I have better stoves, I still felt like a dummy for leaving the fuel tank full of fuel. It was last used in 1996 and the fuel had been sitting in there the whole time.

Deciding to see what damage had been done to old trusty, I pumped her full of air and she fired right up! I burned that entire tank before rinsing and refilling, and there was not one hiccup in the burners. In fact, when I lit the new fuel, there was no noticeable difference. None.

Now, this is not to say I refute claims that fresh fuel burns cleaner... not at all, I wholeheartedly believe it. But I tell you this story just so you know: in this case 10-year-old Coleman fuel can (and did) work just fine, even though it was a fluke to be stored that long.

EDIT: Oh, and by the way, Coleman is still in business and as dedicated as ever. Just two weeks ago, I bought a new check valve and valve assembly from them (for a 440 Ultralight), and asked some questions about an old 2-mantle lantern that, incidently, was stored with the Coleman 2-burner stove. They replied to 2 different emails and even dug up and emailed an old parts diagram for the lantern that wasn't available on their internet site.