Everyone suggests draining old gas before attempting to start a car in storage but how long is that original gas good for ? What's the average shelf life of gas ? Thanks for your knowledge .
Depends on the shelf, really. In the tank of a modern car with a well sealed ventilation system and charcoal canister, in a climate controlled garage, probably several years. In the tank of an old car with a badly sealing gas cap, outside in miserable weather, perhaps a month or two. Yours probably falls somewhere in between.
had a car 6-7 months in storage and started right up. gave a little battery charge- and put it on a tender had another in storage almost 15 years, with gas but at the start of it I added some fuel Stabil or stabilizer many years back. it had about 5 years of turning on occasionally, then about 10 years of just sitting. when I got it back, I actually removed the tank to make sure there was no clogs or rust and the fuel was still clean and not stinky and no rust. Carb needed a good cleaning though.
My brother left a car in the driveway for more than 3 years. His job as a small engine mechanic dictated that he dump old gas out of every lawnmower that wouldnt start each spring and hes a firm believer that fresh gas is all that is needed in most cases. The car with 3 yr old gas started immediately.
The smell test seems to hold up pretty well. If it smells like gas its probably OK, if it doesn't smell like gas, get rid of it. If it smells like old varnish, get rid of it and clean out anything that stuff could touch. Modern gas wasn't very good to start with, so its window of being useable is only for 3-6 months, without having added a chemical mix to stabilize it. A burn test is pretty effective with modern gas. Get enough out of the tank to make a wet spot about 6" in diameter (no larger) on clean, dry cement, away from everything, and throw a match on it to see if it still burns. If the spot lights off, the gas is still good, if it doesn't burn, or is slow to burn, replace it.
I hate to say this, but it does depend on the brand. Some will break down faster than others, I'm sure because of the base stocks that are used. And like Squirrel said, how it's stored can make a difference. Although I had an OT car that sat for several years outside and with a new battery, started right up on the old gas and ran fine. The pre-mix for my weedeater/chainsaw seems to last OK too, a gallon will last me a couple of years.
A lot depends on how well the tank is sealed and the temperature that the car is stored at. In a cool temp with a well sealed tank it could last for years. Outside in the hot sun with the gas cap off, 6 months at best.
Read what Jim posted in post 2 about three times through. My experience is that if the tank is vented straight to the air though the cap or a vent tube it can go bad pretty fast, If it is in a sealed tank that vents through the charcoal filter it can last a lot longer . From my other experience lately if it smells the least bad it is bad and if it just smells like gas it is ok. Still if it is questionable draining the tank and starting over is a lot easier than pulling the heads to pull the valves and clean the carbon that forms on the valves when it forms from running bad gas.
I could be wrong, I think the last federal regulations on gas was made when Obama was president? To lazy to look it up, but those last regulations seemed to shorten the lifespan of our current gasoline. The only experience I have with it was my Uncles truck that had old gas in it. When taking the carburetor apart the fuel had turned to mud. Problem is the truck seldom gets driven. Drive it once then let it sit for a year, then drive it a couple times & sit again .... then add fresh gas to the 2 year old bad gas. ... The tank needed to be cleaned out. My neighbor has a shoebox with a ot motor with FI. I fixed some cooling issues with it so he could drive it. Was overheating & not driven for a year. I then asked him to drive it to run the old gas out of it. Then I would work on a tuneup & adjust the brakes & other work that was needed. Due to health reasons it never happened. Now the gas is 2.5 years old. I will not even consider starting the car with this old fuel. When he is ready I will use the electric fuel pump on the car to drain the tank. Just no way I would start the car with 2-3 year old gas in it. One year old gas was fine to run it, would run a bit rough, stumble a bit .... just run the old gas out & will tune it on fresh gas. 2-3 year old gas, no way I want to chance starting the engine going through the injectors with that old mud they call gasoline. The same neighbor has a beautiful 1964 chebby truck with fresh paint & a sbc 350 .... same issue 3 year old gas. He is doing well, hoping soon he will want to drive them again.
On a humid summer day Put some fresh gas in a glass measuring cup. With the large surface open to the air the gasoline will quickly look like there are 100 mosquito larvae wiggling and kicking in there. The alcohol is pulling the humidity right out of the air, and everything is mixing and dissolving right before my eyes. With a typical tiny hole in a vented cap the process is much slower. The next day there will probably be a 1/8 to 3/16" layer of separated water/alcohol/crap in the bottom of the cup. multiphase/ phase separation. https://enertechlabs.com/wp-content/uploads/2014/03/Phase-Separation-in-Gasolin.gif
I think it depends on what type of gas. Several years ago, I needed to start a couple of my units that had each sat 3 years. The first was a '68 Corvette that had only had "non-oxygenated" (no alcohol) gas in it; a little prime, and it was running fine. The other was a Yamaha V-Max snowmobile that had run only ordinary gas (with alcohol). All four carburetors had to come off and be cleaned and rebuilt before it would even pop. And then there's my current thread on my "Almost O/T race car". I pulled it out Wednesday to see if I could get it started. I expected a lot of problems, since it had been sitting since 2015. The gas in the tank smelled pretty good, although the carburetors were a little ripe. We decided "what the hell, let's try it". A couple of squirts from the priming bottle and it started after about 4 or 5 revs. It took a couple of minutes, but everything seemed to clear out and the engine ran great! (See my other thread if you don't believe me.) I can only attribute this to the fact that I had filled it to the brim with Sunoco 116 octane leaded race gas before I put it away.
When I pulled my '34 PU out of the barn, the gas in the bowl was golden (like it used to be). I changed the oil and gear oil, but I ran that old gas. From what my cousin told me when I got it, it was probably 20 years old. I didn't want the hassle of draining it and disposing of it, so I just ran it and kept topping it up with new gas. Seemed fine.
My experience with bad gas is mainly in motorcycles. I am totally convinced the gas reacts badly to the metals that carburators are made of. I have had brand new bikes sitting on the showroom floor not start after a couple weeks. drain the carbs and get the same gas back in there from the tank and they fired right up. My personal bikes are the same way. FI kinda helps that problem now. I would bet old cars are the same. Just not as exaggerated. Small engines(chainsaws, weed whackers) are even more vulnerable.
Find a gas station that sells clear gas (itll be the one all the guys use in their boats) its expensive but if ypure gonna park it fill her up with clear gas and run the tank half empty, everything will hold up for years. Clear gas has zero ethanol and thats what ruins everything
As much as I love to blame things on corn (I have an actual list which includes my 1st honeymoon), I have had to clean out many gas tanks from the pre-ethanol era, that had turned to turpentine/syrup over the years.
Im not sayin itll last forever but it will last years. Regular gas about 10 months maximum. Premium, year, year and a half maybe. Clear gas Ive had be just dandy 3-5 yrs later. Also destroys the rubber bits inside carbs less....just my experience
I have rescued or resurrected probably 150 cars in my adult life in various states of disrepair and lengths of sitting. This is going to be a long answer and I don't really want it to be but it's the only way I can describe it properly. From my experience it's more of an odor you are looking for when checking If you should drain the gas or not more so than a length of time. I also want to say I don't think sta-byl or similar products actually do anything in keeping the gas good any longer. What I find helps keep gas good longer is it good tight fuel system or tank with no vent to the atmosphere, Also keep the gasoline out of direct sunlight so store in a shed or something like that If it is in the car It's a little more complicated. Give the car a good sideways shake to slosh up the gas in the tank and Stick your nose on the filler tube on it If it still smells like fresh gas vapors It will probably run on it Just fine even if it is 6 months or a year old maybe even 2 years old Just make sure it smells like fresh fuel. One thing worth mentioning but I don't think it really affects anything other than fuel mileage is I have noticed when fuel starts to get old usually the fuel mileage will go down I have no idea why But I've never really given it much thought but my guess is the BTUs become lower as the volatile organic compounds (VOC's) evaporate from the fuel therefore it causes you to give more pedal input so to speak in the gas pedal. At any rate The vehicle should run especially if it's carbureted. (Make sure to have a good fuel filter before the carburetor). If the gas is starting to smell "stale" The overall still smells volatile for the lack of a better word you need to cut it with fresh gas a good rule of thumb is at least a 50-50 mix of fresh and old fuel The more fresh fuel the better, I usually tell my friends to cut older gas using 4 gallons of fresh fuel and 1 gallon of old fuel usually the vehicle will burn the gas just fine The problem is people for some reason seem like they like to park a car with damn near a full tank so this becomes much more difficult to do and realistically your probably going to have to drain some of the fuel out of the tank to get it to mix correctly. If the gas is completely spoiled (rotten) don't even mess with it just drain the tank All the way to empty. And pour the fuel into containers that you can see the condition of the fuel (I like using milk containers with a screw on lid probably not real safe but it allows you a good visual reference). Generally speaking Fresh fuel is almost clear old fuel is very yellow ethanol mix fuel is also usually very clear in color when it is fresh unless it has been dyed, although I don't think any fuel manufacturer is dying their fuel anymore other than off-road diesel but I'm not positive on that. On a vehicle with a catalytic converter I would not run any gas that is even slightly bad It would not want to take a risk of burning up the catalytic converter especially on a more modern car where the catalytic converter can sometimes cost $1,500 or 2000 bucks to replace... On vehicles without catalytic converters to get rid of the old fuel I have taken a gallon to two gallons at a time and poured it into the fuel tank (using those milk jugs I mentioned earlier as I can take the fuel out of the jugs poured in the tank at the gas station and then throw the empty jugs in the trash can at the gas station so I don't got to smell the nasty things). After I pour a gallon or two of old fuel in the tank I fill the tank with 15 or 20 gallons or whatever size the tank is (we are talking about full size big American cars not little economy cars 10 gallon fuel tanks or Ford Model A with a 10 gallon fuel tank but the bohemoths from the '50s '60s and '70s that had huge tanks). All you are trying to do is dilute the fuel where you can get rid of the old fuel and not have any problems. If you choose to dispose of your old fuel this way You will smell the rotten fuel in the exhaust but you won't notice it run any different on most stock non-performance cars (My 1973 Lincoln has probably burned few thousand gallons worth of rotten gas in the 25 years I've driven that car all 1 Gallon at a time, the 460 doesn't seem to care it's just thirsty, My Dodge Flathead 6 also does it care Of course it's probably seven to one compression or something so it'll pretty much run on anything flammable lol. Now let's say the vehicle has been sitting for 30 years we can assume it smells like "lacquer" (horrendously bad) I wouldn't mess with it, It's just not worth the risk but again if you're going to do it my recommendation is cutting it in a 15 or 20 to one ratio to dilute it down to almost nothing. Your big worry about using older fuel or using a fuel tank that had older fuel in it is everything turns to varnish which is a yellow sticky nasty film that reminds you of a more thick honey for a lack of a better word. If the gas tank is vented to the atmosphere there's a good chance about half of the fuel over the years is evaporated and what you're going to have left is a thicker fuel that is somewhat turned into varnish... The varnish will plug up orifices In the carburetor, It theoretically can plug fuel fuel injectors, after it burns it can cook a catalytic converter, It can foul spark plugs, It can leave carbon deposits in the cylinders and on the valve stems... It's nasty stuff to say the least. Hopefully this helps a little and if you don't understand ask me I will be happy to explain myself better.
So with the talk of not venting to atmosphere, where can you vent a tank? Maybe into some kind of desiccant tank? Can’t see using any kind of check valve, tank would eventually suck itself together, I’d think.
It also depends on the gas type. A large amount of gas today has 10% ethanol mix in it, and it can go bad much faster than clear non ethanol mixed gas. Even for winter storage of my cars I still add Stabil for ethanol mix gas, and run the engine long enough to ensure it gets into the carbs too. Seems to work, as my engines fire right up after months of sitting, and run fine.
Weird. I have a whole bunch of old engine powered crap, and have been running E10 since it was adopted. American, Italian, German, Japanese, etc. No issues, once I re-jetted for 14.2:1, instead of 14.7:1. Then again, I don't leave my stuff to rot.
For the purpose of storing during off season, Harley owners have found somthing that works. Ask your Harley dealer for "Liquid Performance" A little goes a long way. The large bottle, my choice, is near 30 bucks, but worth it. It works.
For four-stroke engines, unless your car is running really high compression it will still run fine on old gas. A couple years ago my old two-stroke lawnmower wouldn't run. It took premix. I wet a rag with the gas and lit it, it burned but not like gasoline. I drained it, put fresh premix in, and it ran like a champ. Two strokes and performance engines are much more finicky on octane level than your average 8-9.0:1 automotive four-stroke. However, if the gas in question has ethanol, it seems to go bad to the point of not burning well sooner and causes a lot more corrosion and other damage to the fuel system. Fuel stabilizers help with that.
This week I picked up an AFB Someone had messed up Iwas trying to get accelerator pump passage open filed the float boles with 10% E gas day got hot so I went to the house the next day 1/2 of the gas was gone it probably well over a 100 degrees in the shop.
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