If you watched the latest episode of Fear the Walking Dead (Season 5 Episode 8), then you saw that the show is finally acknowledging problems with gasoline in a post-apocalyptic world. But is the show accurate? Can gasoline really go bad after an apocalypse?
Yes, FTWD was accurate this time. Gasoline can indeed go bad, for a number of reasons. And the more ethanol you have in gasoline, the faster it can go bad. Fuel stabilizers can delay the degradation, but not permanently.
There’s a nice discussion on Reddit here from the FTWD subreddit. They discussed how long it would take for gasoline to go bad, and one person noted that it would take about a year if fuel stabilizers are added. Without stabilizers, gasoline would last about five to six months (or less.)
Diesel gas, on the other hand, can last longer. Microbial growth can produce slime, noted u/HappytheSandman, but filters can make up for that.
RoadAndTrack.com mentioned that gas can go bad as quickly as 30 days if it mingles with the air. Since cars’ fuel systems aren’t air-tight, they aren’t great for long-term storage without taking extra action. That’s where fuel stabilizers come in. Gasoline can turn “gummy” and gunk up the fuel system. Gas with any ethanol is even more troublesome because ethanol attracts water, RoadandTrack noted, which can hurt rubber seals and turn corrosive. A stabilizer can delay gasoline from going bad for about a year. But you’ll want to add the stabilizer before the gasoline has gone bad, preferably when the tank is close to empty, and then top it off with more fuel. Then run the engine for 5 to 10 minutes.
CNN confirmed this in a 2008 story. Although crude oil can last, gasoline is a refined product that is volatile and can degrade over time. In addition, hydrocarbons in gas react with oxygen, producing new compounds that can gum up the gas over time. On top of that, condensation can form inside a gas tank and gas lines, making it tougher to start a car and rusting internal lines and the tank.
A Quora discussion warned that high-ethanol gases can go bad in three months (others said 30 days), while gas without ethanol might last six months (without stabilizers.) However, another Quora discussion noted that if the gasoline is in a clean, stainless steal airtight container, and is stirred from time to time, it could last years. (This helpful information was shared by an engineer at an oil company.) Gasoline is rarely stored this way, though, so lasting this long is rare.
Redditor Dekarde shared an idea for what to do when you need more gas in the apocalypse: “Propane conversion kits exist but you probably won’t find one anywhere outside the company’s who make them. Doing the conversion would require some work to alter or fabricate parts and tweak the setup after installation. Then it would be simple to grab a barbeque propane tank and connect it. A real conversion would add a dedicated propane fuel tank built to withstand crashes but apocalypse you do what you need to.”
Dekarde added: “Another feasible alternative is a wood gasification system as used back in ww2 that’s more cobble together and perhaps more practical with readily available wood fuel, no tanks to fill or find.”
In a discussion forum, someone else noted the same: that in World War II, cars were converted to wood-burning vehicles with a wood-gas generator. This type of generator converts timber or charcoal into wood gas, which after filtering and cooling, can power an internal combustion engine. In fact, FEMA published a book in 1989 about how to build a gas generator when oil isn’t available. This might be a better option than what our Fear the Walking Dead folks are doing.
In a dicussion on Straight Dope, one reader suggested that underground tanks at service stations might be the best source for apocalyptic survivors. Commenter bob++ wrote: “Eventually whatever population was left would revert to a level that it could sustain. Water is a good source of power, wind too. They can be used directly to drive machinery, to grind corn for example, or indirectly to generate electricity.”
If you haven’t had a chance to watch Fear the Walking Dead yet, you can catch it on Amazon here.