I have some Sunoco 100 that is about 3 years old and it works just great in my snowblower, lawn mower, weed whacker, and my neighbors 20 year old pressure washer. I believe that it last a long time in a sealed container.
And you don't need to guess.......my answer is the best one on the interwebs
Sorry.....couldn't resist based on the comment above about which one would you believe to be the best