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I have a 5 gallon can of gas from 8 months ago. I did far less yard work than I intended. I have fuel additives I could use. Joogle says 3-6 months, but I am looking for "real world" answers.

Please only answer if you know what you are talking about, and remember, I already used the internet to try to find my own answers.

Edited: Fuel is 89 Octane with UP TO 10% ethanol added.

I have a 5 gallon can of gas from 8 months ago. I did far less yard work than I intended. I have fuel additives I could use. Joogle says 3-6 months, but I am looking for "real world" answers. Please only answer if you know what you are talking about, and remember, I already used the internet to try to find my own answers. Edited: Fuel is 89 Octane with UP TO 10% ethanol added.

(post is archived)

[–] • 5 pts

If sealed , quite a long time, first remember this you have no idea how long it’s been stored before it made it to your pump ....... I used to build high end race engines we sent race gas off to a lab for octane testing one time to test this same subject....... gas one year old or more properly stored and fresh from pump had same properties and octane Levels ... evaporation and oxygen is what ruins it leaving gunk behind ..... the closer to full and more airtight the container the longer the shelf life ..

[–] • 5 pts

In a good jerrycan protected from light it should last at least a year. That's from personal experience

[–] • 0 pt

It has been sitting unopened since I bought it.

[–] [deleted] • 4 pts

Modern gas is shit. It smells bad, has no octane, and goes bad fast. I miss real leaded gasoline and before you say anything about lead being bad and lowering IQ's look around....

[–] • 1 pt

Lead was good for engines. Not good for humans, but good for engines.

[–] • 0 pt

I miss real leaded gasoline and before you say anything about lead being bad and lowering IQ's look around....

Jesus. You want to make it worse?

[–] • 3 pts

professional MC mechanic since 2000 ~ I make a lot of money in the spring cleaning carbs.

Bunch of variables. The main issue is varnish (gas turning solid through evaporation and oxidization), this doesn't bother gas in a can beyond getting a layer of slime/sludge in the bottom. Gums up fuel filters though. Without any kind of additive, in a cold/dark place, 4~5 months of storage isn't unreasonable. Add something that stabilizes the fuel (basically slows the oxidization process, I like Sta-Bil brand for ethanol) and you can essentially double that time. Heat and light shorten the time, so if you're somewhere hot, cut the numbers in half.

Where you need to take care is with the engines, Especially if they're carburated. Just "running till empty" leaves the carb bowl about 1/3~1/2 full and speeds the process of varnishing. Best to use the drain screw on the bottom (not all carbs have them, my Honda mower doesn't) to get Everything out. Fully fill the tank to get as little airspace as possible (or fully drain the tank), and be ready with a fuel filter early the next season.

FWIW, don't waste your money on higher octane fuel for yard equipment, just a waste of money (you getting pre-ignition on your mower?) AND it's a less often bought fuel so more crud in the tanks (typically). You want your fuel to be from a station with as much turn-over as possible. If possible, bought 24 hours or more after they've had a delivery (deliveries stir up the sediment and water that's found in all fuel holding tanks).

[–] • 0 pt

don't waste your money on higher octane fuel for yard equipment

I always use the best gas for my lawnmower. Why? It doesn't have alcohol mixed in with it, and thus can't absorb water. Water will mingle with alcohol, and when you have gas with alcohol mixed into it, you get water with the alcohol. It causes rust. Also, I find that the high-test gas starts easier after the mower has been sitting over the winter.

[–] • 0 pt

Unless the pump says ethanol free, all grades of gas will have ethanol and will varnish in months during summer- especially in the humid south.

You are much better off with plain ethanol free- usually sold as 89 octane.

[–] • 2 pts

I've been storing a car with the same 89 octane gas for a year and a half. Every 6 months or so I start it and assuming the battery doesn't need charging it fires up immediately. I considered putting a fuel stabilizer in but I saw a video that compared several that are on the market and there was no benefit found in using them. The conclusion was that gas without ethanol is the most stable, mainly because ethanol is hydrophilic.

It's 'common knowledge' that gas goes bad but no one seems to know how long it takes to happen. Clearly 3-6 months is very conservative estimate.

[–] • 0 pt

Butylene is already in your gasoline. Butylene is fuel stabilizer.

[–] • 1 pt

Ethanol is hell on small engines i would get new gas.

[–] • 1 pt

I am thinking of adding some marine grade stabilizer and putting it 40/60 in my car. Bad idea?

[–] • 0 pt

Should be ok if its just a small amount. I wouldnt make it a habbit

[–] • 1 pt (edited )

With ethanol, I wouldn't use it past 6 months unless it was in an engine I really didn't give a fuck about. If you have to store ethanol jew gas, hit it with some stabilizer before you store it. And I would never use ethanol gas for 2-stroke mix if that's what you're intending.

With non-jewed gas, if it's stored airtight and in a cool/temperature neutral spot away from sunlight, I'd be comfortable up to a year for sure. I have never really gone beyond that.

Side note, ethanol is an anti-gelling agent. Can't make napalm with ethanol gas. Everyone should have some Flash 21 A/B.

[–] • 1 pt

Tips for fuel storage AND tips for the revolution...you won't get that from the Car Doctor.

[–] • 0 pt

Oh, fuck, never use a gas stabilizer. I used gas stabilizer in my roto-tiller and it wouldn't start the next spring. Nothing I did would make it start. I finally took it into the shop, and they changed the carburator. Now, I know they didn't need to put a new carburator on it. The fuckers were too lazy to clean the carburator. I stopped going to that shop, and it is now closed permanently. Gone. But the experience taught me one thing -- never, under any circumstances, use a gas stabilizer in any engine.

[–] • 0 pt (edited )

It wasn’t the stabilizer, it was moisture that was absorbed into the ethanol and the gas varnished. Stabilizer extends the life, but won’t completely prevent gas from varnishing. I guess if you used Chinese or Mexican made dollar store stabilizer it could’ve been the issue....

It’s always the sludge that fucks up the needle.

[–] • 0 pt

Now, I know they didn't need to put a new carburator on it. The fuckers were too lazy to clean the carburator.

First I thought 'jews', then I thought 'niggers'

[–] • 0 pt

If you want to store gas with ethanol then you should add fuel stabilizer. Especially if you are keeping it in a vehicle's gas tank. the ethanol will separate and rust the inside of the tank pretty bad.

[–] • 0 pt

Gas will still work after a year in a tank. But it won't have as much pep as when it was new. How do I know? I own a motorcycle. It sat for a year, and then I decided to ride it. But it wouldn't start. Just wouldn't fire. I did one thing -- I syphoned the gas out of the gas tank, and put new gas into the tank. It started on the first touch of the starter button.

I've used gas more than a year old in lawnmowers, and they will run on it, but probably not with as much pep as they would have had with fresh gas. Gasoline is a very perishable substance. The whole "Road Warrior" scenario is ridiculous, where you see them trying to get gas out of tankers when it's been sitting for years.

[–] • 0 pt (edited )

Probably 10+ years. I had a car sitting in my garage since 2015 because I sold it and the transaction never was finalized until 3 months ago. I jump started it and it drove perfectly with the old gas no noticeable loss of performance. The tires have flat spots, the battery was replaced other than that there's nothing wrong with it.

[–] • 0 pt

I have been storing 100 gallons of 87 octane in 5 gal Nato military cans for about 8 years now. I rotate my fuel every 12 -16 months with no problems. (Stored inside with temps between 50-90 degrees)

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