How long is sta-bil gas good for?

I have a car that sits in a garage and is rarely driven, I added a double dose of sta-bil around the 1 year mark of it sitting and it has sat for about 2 years now. Is the gas still good? When the gas does go bad, can it damage anything or will my car just have bad performance until I run out of gas and put in new gas? Also if I “top up” the gas by adding a bit on new gas can I keep the old gas in the tank for years?

24 months.

Adding new gas to gas that has sat for a long period of time does nothing to make the gas that has sat last longer.

And here’s another piece of advice.

Follow the instructions on the product container. Deviating from the instructions may have negative results.



I agree with the 24 months. That’s about the extend so start it up and run it and start over.

IF the gas was fresh and contaned alcohol (ethanol) I’d not keep it any longer than 12 months. 24 months for ethanol free fuel. BUT the Sta-Bil MUST be added when the gas is fresh, not a year later.

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The container of Sta-Bil that I have mentions nothing about whether the gas has ethanol or not.

It just states, “Keeps fuel fresh for up to 24 months”.


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If the gas smells good Start it up and run the gas out, my thought. If the gas smells spoiled dispose of it properly and start over. A few older vehicles with old gas that smelled ok took some starting fluid to get going, ran ok but happier with new fuel. Change plugs maybe after old fuel is gone.

I was expressing my opinion, not Sta-Bil’s instructions.

Can’t speak to how best to deal with fuel issues on long unused automobiles, but I get best results with my lawnmower to simply empty the gas tank before placing it in storage for the next 9 months. None of the other methods I’ve tried – including stabilizing additives – are as effective as just emptying the tank. I just recently had need to use my lawnmower after a 9 month hiatus, and after fueling and cleaning the air filter, it started right up on the second pull.

A friend had a van he rarely used and kept the tank basically empty. After 3 or 4 years, the tank rusted out from water that condensed inside.

Sta-bil is a brand, and they make more than one product. Just read the label, and if you can fill the tank with ethanol-free gas, do it.

Is it better to siphon out the old gas or let it run while sitting?

I would just drive it, let it run. It’s pretty hard to siphon gas now I think but what would you put it in anyway, and how to dispose of it?

How old is the gas that’s in there? How full is the tank?

Make sure you run the stabilized gas through the entire fuel system after you add the stabilizer.

I’ve waited as long as 18 months between buying gas and never had a problem, or used Sta-bil. I add a bottle of carburetor/gas line/injector cleaner every year.

…and I’ve had problems with E10 that was less than 12 months old in a motor home.

A friend of our family spends most summers in Europe and parks her car at her brother’s farm She has a fresh oil change and puts Stabil in the tank and has never had a problem restarting the car after 6 months.

How long will it take to burn through half a tank of gas idling?

A long time but why not drive it? Go to the Dairy Queen or something on a nice summer day.

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Figure about a quart an hour.

An auto mechanic wouldn’t charge much to just drain the gas tank. Get a quote for that job from a shop before doing something like idling the engine for 8 hours.