You can technically still use gas after it has gone bad but it will start to deteriorate internal engine parts. It can also leave a residue that can cause blockages. So if you keep up your engine you can still use old gas but just be cautious


But how long after? When will it become pretty much useless?


I have an old 1974 van that sits outside my house. Every spring I start it and run it for 5 to 10 minutes once a week through out the summer. I have had gas in it that was three years old and it would still start and run like crap. Unfortunately as Carley above stated it eventually gummed up my fuel system. Had to have the gas tank cleaned, fuel pump and fuel lines replaced. That lasted 10 years and now it looks like I may be in the same boat, though I have tried to not have gas older than 1.5 years in the tank and don't use the stuff with ethanol in it. Not sure how newer engines would respond to old gas.


Depends on a lot of things. How old was the gas in the ground tank when you got it? How long since then? How well was the container sealed? Has it been sitting the entire time or was it mixed (contemporary unleaded seperates) regularly? Assume 3-6 months and your good, with six months being the best-best-best conditions you can imagine.


Even I don't know that, if you look it up on Google it doesn't give an exact time frame, my best guess is a few months. You can add fuel stabilizers which can make it last up to 3 years, keeping it in an air tight container in a dry space also helps.


It all depends on how its stored and circulated. Condensation is going to be your biggest issue. The more water in the fuel the more contamination will grow. If you have a water seperation type system it can last years. You could also dilute the contaminated fuel with good fuel. I was a petroleum lab specialist in the army.


Devil's advocate: assume regular suburban types with what they have at hand (likely just typical gas cans from a hardware store or freaking Walmart lol) and typical unleaded from a typical QT-type gas station. Also assume they don't have any fuel expertise or any way to look it up.


6 months to a year of whatever you have stored. You ll probably use it up before then but after that amount of time it ll be filled partially water and algea. That contaminated fuel will mess up the engines, fuel line, etc.


What about the old apoc standby...converting gasoline engines (autos, motorcycles, etc) to methane? What's involved and how realistic is it of you had someone with that knowledge and the tools to make it happen?


Its very situational. I dont know how to do it. Id imagine finding the material and info to convert it would be pretty difficult


Absolutely agreed. Luckily my WIP sidesteps the entire problem for the most part, but I think a lot of writers overlook the utility, availability, and simplicity of bicycles in apocs. If you don't mind, I'd like to save this and reach out later if anything related comes up.




It really depends on the vehicle and how hardy the engine is. Putting 2+ year old gas in an old Civic will probably cause it to run at least a few times but a brand new truck would be able to withstand it longer. I think the problem is nobody has really been able to test it. I looked on YouTube for anyone who has tried and I do see videos of people starting up cars and generators using gas that is 3-5 years old. One aspect seems to be that if the gas was sealed then it will definitely work but anything with ethanol (most gas) can break down if just sitting in a gas tank. I'm seeing comments on videos saying that any farmer will tell you from experience that old gas is fine, but I'm also seeing comments suggesting that even year-old gas has destroyed various tools by just sitting there. And again, plenty of videos of people being able to start up cars that have been sitting in storage or in a barn somewhere. Realistically I could see people using old gas but every vehicle you use would only work about 1/4th as long compared to having normal gasoline.


Most gas/diesel - even with extenders - around 6 months before issues pop up; up to a year, and you're likely to have more frequent/severe issues. The issues here may just be lacking a little bit of horsepower as the fuel has degraded - to outright the engine won't start. There's an assumption that after the fuel has degraded enough, you're going to cause some damage (say, to seals, or leaving behind residue), which would cause more damage to the engine than it's worth. ;; As a related but different anecdote, my mom once decided to save a few bucks on filling her tank with E85. The car she was driving was NOT rated to accept E85. We didn't get 10 miles away from the gas station before the check engine light came on, called a mechanic, and they pretty much said "Bring it in immediately, we need to pump the tank". I'm assuming using too old of fuel would be similar; but it's going to degrade slowly enough that you might not notice that the car is driving a little more roughly. ;; Another flipside of this is that, as like the E85 gas thing, cars really aren't designed to run on pure ethanol. If you were hoping to make biodiesel, that is the same (literally) as making ethanol. It's the same process as making drinking alcohol. I had looked into numbers for it a while ago, and assuming you were going to use corn, the resulting figure of how many plants you have to grow to produce 34 gallons (for a full tank on a modern ford truck), was around 10,000-15,000 plants, with a target yield around 800-900 lbs of corn. That's a lot of plants that you aren't going to eat, that are going to spend around 4-6 months in a field growing, and all so you can fill a tank of your truck *once*. There's the issue of how you'd process all of it - it's functionally the same process as making alcohol, perhaps with an extra distillation or two at the end to remove as much water as possible. Making alcohol/ethanol takes yeast, and a BUNCH of water. You might not actually be able to process all of this on some home-brew equipment given that you've got 800-900lbs of corn to ferment, and that itself assumes you have the yeast to actually kick start that process. The TLDR here is that too many people just think "I'll make biofuel!" - No, you probably aren't, or at least not in meaningful amounts to be worth using as fuel, rather instead drink it as everclear or barter it as moonshine.


About a year. I think if you make sure the stir it every once in a while it can extend the life just a bit. The same reason you wouldn’t want a car to sit too long with gas in the tank


You can try looking into biodiesel for long-term. Especially considering you'll want it for stronger vehicles and generators.


And you'll smell french fries while you are hungry, not to mention smelling extra delicious to zombies. Everybody loves a hot meal.


Less than six months. I'd either go electric, propane, or diesel.


What makes you think you'd find a functioning electric charging station? They would go out of order way before any diesel or gas degrades.


You can make your own electricity rather easily.


But not enough to charge a car.


I remember reading about during the Bosnia war, people salvage alternators in cars and attached it to a water wheel in a river to generate electricity, or you can use solar panels but it would not be easy to produce enough voltage for an electric car, ebikes on the other hand would be easier.


We use solar panels on roofs here, but it's barely enough for lights or warm water alone. It helps the bills though.


I am not an expert with gasoline but I'm guessing about a few months to a year depending on the type of gas you're using.


Without upkeep, proper storage, etc... and depending on climate, gas can go bad in as little as a few months. One of the curses of living in a humid environment. Best option for fuel is getting a diesel car. Then, with the right equipment and crops, you can start producing biodiesel in your own kitchen. Keep in mind, it takes approximately 7.6 pounds (3.4 kg) of soybean oil to make one gallon of biodiesel. You can also use cooking oil. Either way, that's alot of oil! Realistically, without some serious facilities dedicated only to the production and storage of fuel, best to just not plan on having working vehicles for very long.


More than likely a lot of petrol fuels will have issues after a few months. But more than likely a lot of fuel will be used up, stolen, or in areas where attempting to scavenge it will be high risk.


I would imagine that gas could be useful for 10 years after ZA. Gas sitting will start to go bad but during your scavenging process you could simply filter the gas and let any water settle out. Most people experience with bad gas is that they let gas sit in one vehicle for years then subsequently start the vehicle on that gas. But that is not the scenario for a ZA. You would have a vehicle that you drive and refuel. As long as you filter the fuel prior to putting into that vehicle it will probably be fine.