Letter: Long-Term Gas Storage

Hi Hugh and Jim.

I am trying to figure out what to do regarding safe long-term gas storage.

There are some that recommend treating gasoline with Pri G and sticking it in a HDPE plastic drum filled to the top. Others suggest that if you treat the gas every year with Pri G it will last “forever”, even ethanol gas. There seem to be a few common sense caveats, like cooler is better, temperature swings are bad, and you need to keep the tank full, et cetera to give themselves an out. I find this hard to believe.

I have tried the plastic barrel thing with ethanol gas and am three years into it. I am blending about 50/50 with fresh gas. One of my vehicles has the “check engine” light on, and the owners manual suggests I got a bad batch of fuel.

Ideally, I would bury a tank, but that isn’t possible. I am not going to store the gas in a climate-controlled environment as some suggest.

I have found a source of 91 octane ethanol-free gas. I have found a rust-free 275 gallon fuel oil tank. My thought is to paint the tank with rustoleum a few times and hide it in some shrubs, out of the sun, and treat the gas with Pri G and keep it full. The temp will range from minus 5 to 95 here. I am considering wrapping the tank with foam insulation (or bales of hay covered with a tarp), but I think perhaps condensation will form on the tank and the tank will not dry out and that will expedite oxidation of the steel tank even with the rustoleum paint. Perhaps epoxy paint? Another concern is expansion/contraction. With plastic I think it is less of a problem but with metal if the tank is sealed, could a seam pop or could metal fatigue occur over time? I could add a small vent and put a “balloon” over the vent. Or if the tank is full enough, could I not worry about the moisture/condensation inside as ‘Pri G’ will cure all problems as folk from Pri G suggest?

Do you have someone credible with experience in this for advice? I think the whole community would benefit from an honest discussion on this. There are very many variables to consider.

HJL replies: There is certainly a significant amount of bad/misinformation along with alot of marketing hype that is centered around selling product. Here is the problem with gasoline in a succinct form:

Gasoline is a combination of petroleum distillates. Some are light, some are heavy, and there is everything in between. Over time, the lighter distillates evaporate leaving the heavier ones behind. Stabilizers can slow the process but not stop it. You can rejuvenate gas by bubbling butane or propane through it (a process which I am sure I don’t have to further explain the dangers of; this would fit in the “famous last words” category of the proverbial red-neck: “Here, hold my beer!”).

The reason liquid petroleum gas (LPG) lasts forever is because it is fully contained, typically in a thick sealed metal container, and nothing evaporates. Gasoline is usually stored in plastic containers, which leak. A vented container will breath these lighter distillates with temperature changes, which is why that shed with the gas can inside it always smells like gasoline even when the lid is tightly on the can.

Ethanol complicates the issue because it is hydroscopic and will absorb moisture out of the air. When enough moisture is absorbed, it separates out. The ethanol also evaporates leaving the water behind.

The only way you can reliably store gasoline for long-term storage is to keep the lighter distillates from evaporating, which means you need a container that is completely sealed and strong enough to handle pressure and some abuse. (An LPG tank comes to mind.)

The government, of course, does not like this idea because you end up with a pressurized container that tends to spew liquid over everything when you crack it open. (The original NATO gas cans are a prime example and are pretty good but not legal, especially in Kalifornia for this reason.)

In short, a non-sealed container will not make really-long-term storage feasible no matter how much stabilizer you put in it. The lighter distillates are necessary for the consistency of gasoline. A sealed container makes for a potential explosive device (never mind that the government is okay with LPG tanks; you just apparently can’t have pressurized gasoline tanks).

Personally, if I wanted to store gasoline for an extended period of time, a converted 1000-gallon LPG tank is how I would do it. Don’t expect to get a county permit for that any time soon though, and it is cost prohibitive, even if you go with a used tank. Ideally, you should rotate through your gas storage so you are always using the oldest while storing the freshest.

A much better alternative is to go with at least one diesel vehicle and store that fuel instead. There are far fewer issues involved in storing diesel or kerosene.