How bad is 18-month old gas? What should I do?

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First post! Hi!

For various and health reasons, I had to let a car sit, not started even once, for 18 months in an unheated but attached garage. Due to poor planning, the gas tank has been nearly empty all this time. No stabilizer was used.

This year, I'm able to insure the car in May and thus plan to fire it up and immediately drive it over to a gas station (a few blocks away) and fill up the tank. The thinking was this: if the little amount of gas in the tank is now of marginal quality (due to sitting so long), the 25 gallons of fresh gas that it takes to fill the tank would "overcome" any deficiency and the gas would now be essentially 95% pure and fresh 94 octane fuel.

At least that was the original plan... Recently I read, on a non-automotive forum, some people saying that gas left so long in a tank is now unusable. And that it could even harm the engine. This left me a bit worried so I'd like to ask a few questions here, a forum with much more knowledgeable members:

1) is the gas in the tank indeed bad for the engine?
2) what should I do about it?
a) go to the gas station with a jerry can and fill the tank with 5 gals of fresh gas before attempting to start it and drive over and immediately fill it
b) siphon as much gas as I can out of the tank and fill it with 5 gals of fresh gas and take it to the station to fill
c) proceed with my previous plan and just start the car with the little (and 18-month old) gas that's in the tank now and go fill the tank with fresh gas.
d) something else I haven't thought of? Please expand.

If it matters, I should say that winters are not very cold where I am. It rarely gets below freezing . This year, outside, I don't think it dipped below freezing even once--and thus it would have been warmer inside the garage. Battery has been on a smart-charger.

The engine is a normally-aspirated multi-valve modern engine (2006, Bosch Motronic controlled) that is high performance and highly-tuned (temperamental) even when left stock (the engine is stock).
 
Originally Posted By: BobandWeave

a) go to the gas station with a jerry can and fill the tank with 5 gals of fresh gas before attempting to start it and drive over and immediately fill it


This.

Add a good PEA cleaner like Techron or Gumout Regane to the 5 gallons. If you can get the car to fire and run, the new, highly concentrated cleaner treated gas will quickly fill the system. Drive around a bit to flush most of the 5 gallons through. You will be OK if you accomplish this.

Then, run another full tank of "Top Teir" gas, with 2X the concentration of the same cleaner.

Good luck and welcome.
 
If you can start the car, just drive it to the fuel station and fill up. If it won't start, take a jerry can to the station and get some fresh fuel in there..

A full bottle of redline will clear up any residual goop left in the tank/lines/injectors
 
Look for mice nests in the air intake/ filter. But for gas, what's in there's, in there. Hit it.

Drive gently to the gas station, being in high tune you don't want "the knocks". Also your brakes will have surface rust and won't be that great.
 
Good gas + bad gas = bad gas. Start it. Take it out and fill it. Hope for the best. Skip the premium and the additives. Change the FF after a couple of tanks. Be sure to give the whole vehicle the once over before going on the road.
 
Originally Posted By: gfh77665
Originally Posted By: BobandWeave

a) go to the gas station with a jerry can and fill the tank with 5 gals of fresh gas before attempting to start it and drive over and immediately fill it


This.

Add a good PEA cleaner like Techron or Gumout Regane to the 5 gallons. If you can get the car to fire and run, the new, highly concentrated cleaner treated gas will quickly fill the system. Drive around a bit to flush most of the 5 gallons through. You will be OK if you accomplish this.

Then, run another full tank of "Top Teir" gas, with 2X the concentration of the same cleaner.

Good luck and welcome.


I would do this and not attempt to start it with 18 month old stale gas.
 
If you have a pressure test port on the fuel rail, press its schraeder valve in and see what comes out, if it's "gassy" or "other".

You'll have to cycle the key to prime the system.

Gas "durability" is really all over the map, noone on the internet is going to know for sure.
 
If you're that concerned, fill a five gallon can (or whatever you have in Canada) at the station and pour it in the tank before you fire up the car.

If the gas has gone stale in only 18 months, it wasn't any good in the first place, imho.
 
My friend stopped over this past Friday night to ask for my help in swapping transmissions in his '55 Chevy stored in his barn. I asked him the last time he had driven it, he said he started it for the first time in seven years last week. He said it took a bit of cranking and a few shots of starting fluid, but once it started it fired right up and ran fine. Seven year old gas (it did have Stabil in it). He's about the most honest person I know so I have no reason to doubt him. He did say he could smell the gas in the carburetor and it did smell pretty bad, but the engine ran fine (crate 350).
 
Unless the gas you last put in it had a high ethanol content I wouldn't sweat it.
I have fired up engines with gas at least four years old in the tank with no ill effects.

Claud.
 
A few years ago I bought a 2004 Ford Taurus that sat outside for 3 years without moving. After I replaced the battery and the fuel pump (which had frozen up), the car ran fine on the 3 year old gas - it had more than half a tank. I drove it for about 20 miles before I had a chance to add some fresh gas to what was in there. I'm sure the gas in my 99 Aurora which sits in an unheated garage and doesn't get out much is 2-3 years old - not a huge deal. If I were you I'd get 5 gals of fresh gas to top off the tank and then drive to the gas station for top off - case closed.
 
The question should be is the 18 month old gas real gas or is it ethanol blend garbage. I've seen lawn mowers and snow blowers that sat for shorter periods of time without draining the carb and the inlet screens to the carb were plugged solid, the float was stuck and the [censored] in the bowl smelled like terpentine. Ethanol gas is a scam and is a poor substitute to real gas. It is hygroscopic and the fact you left your tank empty has allowed it to condensate much more than if it was full. I would suggest getting a good fuel stabilizer like Stabil or Valvtect. Skip the "dry gas" additives. And fill your tank with at least 5 gallons of fresh gas. 10 would be better. You want to dilute it as much as possible before running it through your engine. Once you run through a tank of gas I would change the filter as a precaution.
 
Welcome!

Lots of excellent wisdom here already, and I agree that the more gas you can add to the old gas the better.

But before you add any gas to the tank, be sure to check the fuel pump to make sure it's working. More than once, I've seen a fuel pump "lock up" from sitting unused.

If that has happened, lay a board (scrap piece of 2x4 works well) across the bottom of the tank and hit it repeatedly with a hammer. Sometimes this works to "vibrate" the pump loose and it will work again, but you'll be running on borrowed time - change the pump asap.

If your fuel pump is dead, and pounding will not bring it back to life, you will have to drop the tank to replace it, (assuming it's in the tank). That's a bear of a job as it is without the added weight of several gallons of additional gasoline.

Be sure and check all your fluids as well before attempting to crank it up.

Good luck
smile.gif
 
Cars have bigger everything... lines, etc than OPE and can handle little bits of junk, loose varnish, etc better. And their fuel systems are more sealed against atmosphere. I have high hopes.
 
Originally Posted By: eljefino
Cars have bigger everything... lines, etc than OPE and can handle little bits of junk, loose varnish, etc better. And their fuel systems are more sealed against atmosphere. I have high hopes.


+1
 
I left a 93 Suburban at the house I owned and was paying for when I decided to leave and live elsewhere because of a psycho wife (now ex). I got the Suburban 3 years latter and had months of trouble with clogging multiple filters, replaced the fuel pump, found some debris floating in the gas tank. A real PIA. I think new E10 gas kept dissolving crud that had formed when the Suburban sat. I should say that a year or two before I left I changed the fuel pump myself and the tank was pristine.
 
i think it would be fine to start it the way it is and drive to a station and fill up normally
it's not unusual around here for small used car lot to have cars that long with the same gas, once gassed up i would drive on the freeway for a few minutes if possible
i would expect to have a dead battery, and check tire pressure also
 
The solution to pollution is dilution...add 5 gals of gas and drive to the nearest station and fill up. Then add a bottle or two of techron and fuggedaboutit
 
Originally Posted By: eljefino
Cars have bigger everything... lines, etc than OPE and can handle little bits of junk, loose varnish, etc better. And their fuel systems are more sealed against atmosphere. I have high hopes.
Yup a car will be able to handle it. My lawnmower wouldn't run last weekend with 10 month old gas in it, after draining and refilling with fresh gas it ran.
 
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