Does Gasoline Go Bad Like in The Last of Us Episode 4?

The Last of Us episode 4 “Please Hold to My Hand” on HBO sees Joel siphoning gas from cars, as you might well do in a post-apocalyptic world. But he remarks that gas breaks down over time and the fuel he’s gathering is almost water. But is he actually correct? Is the HBO The Last of Us series right in episode 4 about gas breaking down and that gasoline can go bad?

Yes, Gas Does Break Down, but It May Be a Little Worse Than Joel Describes It in Episode 4

Joel is basically correct. He likely doesn’t mean that the gasoline is literally water, but gas loses its effectiveness over time to the point where it’s as useless. As confirmed by oil giant BP’s own fuel handling guidelines, gasoline can “last” for a year when stored in a sealed container. In other words, you can come back to it a year later and it should still be as effective.

But when you put it in the tank of a car or some other equipment such as a generator, it’ll start to break down and oxidize. You can find a more detailed scientific explanation here, but after three-to-six months on the outside, it’ll have lost a lot of its combustibility. Diesel lasts longer than petroleum and could last up to 12 months in a car’s engine before it starts going bad. However, there are bigger problems associated with old fuel.

As either gas or diesel break down, they get “gummy,” which, in turn, can clog up a car’s engine. So, even if Bill had serviced his truck on a regular basis, by using old gas Joel is damaging the vehicle. But again, it’s not like he has a lot of choice.

So is there anything that can be done to stop gasoline from going downhill? After all, oil’s been in the ground for millions of years — but its refined products are much less hardy. What you can do is add fuel stabilizer, which, while opinions vary, could keep fuel “good” for up to three years.

Survivalist Bill seems like the kind of man who would do that, but the gasoline that Joel is siphoning from regular cars won’t typically have it added. There’s also no way to reverse fuel breakdown, and since virtually every oil refinery will have shut down, there’ll be no new gasoline on the way.

Twenty years later after Outbreak Day, Joel is correct to expect very little from the gas he finds. So, yes, episode 4 of the HBO The Last of Us series is generally right that gasoline goes bad as gas breaks down.