How long is gas good enough

[bigtiller]

I don't drive my 2007 GMC pickup very often, because Mrs.tiller's little Malibu gets pretty good gas mileage.
I put STP gas treatment in every tank of gas for the GMC and record the date and mileage. Today is exactly 6 months since I filled it up and it still has 1/3 of a tank of gas.

I know I should just go for a ride and burn the old gas up but I am wondering how long a treated tank of gas can go before doing more harm than good.

 

[RustyA]

If it were mine I would top it off with 91 octane as if it was 87 six months ago it's probably below 80 octane now.

 

[oosik]

I put Stabil in the gas for my ATV & chain saws. It says it is good for up to two years. What does the STP say on the back of the jug?

 

[kthompson]

No doubt six month old gas is not as good as fresh but over the years have used gas at least four months old many a spring time in lawn mower. Have boat with in board gas tank and hope year old gas is fine for been in shop for that long. Think finally have drive and upholstery repairs and updates done.

Like the advice of topping off with high octane.

 

[bigtiller]

I put Stabil in the gas for my ATV & chain saws. It says it is good for up to two years. What does the STP say on the back of the jug?

It doesn't say anything about longevity, just the usual lawyer speak about danger, combustible, children, etc.
The only thing it says is... save gas, prevent freeze ups & deposit build up.

My dealer/mechanic recommended using any product like this on a regular bases to help keep the injectors clean.

If it makes a difference, I usually buy ethanol free 89 or higher octane or gas.

 

[lilranch2001]

It doesn't say anything about longevity, just the usual lawyer speak about danger, combustible, children, etc.
The only thing it says is... save gas, prevent freeze ups & deposit build up.

My dealer/mechanic recommended using any product like this on a regular bases to help keep the injectors clean.

If it makes a difference, I usually buy ethanol free 89 or higher octane or gas.

+1 :thumbsup:

 

[Oldoak]

I put Stabil in the gas for my ATV & chain saws. It says it is good for up to two years. -----------------

Yep, been using that for years.

"How long is gas good enough", depends upon who you ask. As you are sure to find out here. :laughing:

 

[TractorGuy]

My motorcycle has been sitting a year. Fired it up the other day and it ran fine.

 

[3Lfarms]

I filled the generator tank on my toy hauler and treated it with both Stabil and Seafoam. That was 4 years ago, and the generator starts and runs fine and powers both A/C units no problem. It wasn’t even non-ethanol fuel either.
I will run the genny this summer till it’s gone, then fill it with fresh fuel and treat it the same way.

 

[MossRoad]

I don't drive my 2007 GMC pickup very often, because Mrs.tiller's little Malibu gets pretty good gas mileage.
I put STP gas treatment in every tank of gas for the GMC and record the date and mileage. Today is exactly 6 months since I filled it up and it still has 1/3 of a tank of gas.

I know I should just go for a ride and burn the old gas up but I am wondering how long a treated tank of gas can go before doing more harm than good.

Let's say you have a 15 gallon tank. 1/3 means you have 5 gallons left. Just top it off with 10 gallons of fresh gas and be on your way.

 

[rangerfredbob]

It honestly depends on a few things. As stated above the octane rating goes down as gas ages which depends on engine and usage.

On an '07 GMC I'm going to guess you have one of 3 engines, a 5.3L, 6.0L or 8.1L. None of those engines are really high compression so really won't care about octane unless they are worked hard (towing or hard acceleration). Even if you are towing with it, load it up and take it easy to the gas station and top off the tank. The LS engines (5.3L or 6.0L) are known for being tough, people turbo stock engines all the time. 8.1L engines are very tough and use enough fuel that it likely won't matter what it's fed. The higher the octane the slower the fuel burns to resist predetonation which happens at high cylinder pressures normally coming with compression ratios above 9.5:1 which none of those engines have. Any of those engines below about 3000rpm will live just fine with sub par fuel, if you rod on it you could have issues, but it would take time...

 

[fishheadbob]

My uncle the refiner would have replied that your gas is several million years old, what's a few months.

 

[bigtiller]

I think I'm just going to have to drive it more often. I found out some where this week that the STP gas treatment has a shelf life of 5 years. I bought 2 cases of the stuff (24 cans) before I quit driving it. So at this rate it will take me about 8 years to burn the remaining bottles up.

 

[radios1]

untreated gas turns to varnish after a long time, and will gum up your fuel system. treated gas may be good for 2 years..