STA-BIL
Fuel stabilizer $4.97 at Walmart
I think farmers store fuel and would have answers to questions like this, but I would imagine that they also use it quite a bit, depending on the time of the year.
Not sure about a year and a half, but gas stations seldom (if ever) run their tanks dry before refilling.
It really depends on where and how the barrel is stored. If is kept somewhere cool and is 100% sealed, it should last quite a long time. It’s when it’s kept unsealed and the temperature varies widely that it goes bad, mostly from the constant expansion and contraction and the associated moisture that is pulled in because of this. In theory, if it can’t expand and and contract due to temperature changes, it shouldn’t absorb moisture or evaporate the light vapors that keep it fresh.
keep it in yer attached garage next to the pilot light of yer gas water heater,,,
Bkmk
As long as the container is airtight, it should stay good forever.
Not having ethanol will extend the life. You want to keep the barrel as full as possible and we’ll sealed. That keeps the condensation and evaporation to a minimum. A well sealed, refreshed, none alcohol, gasoline with stabilizer should last a while.
But…with modern engines their design is much more finicky than a 1975 V8 with a carb.
You can search this subject on you tube and get a good answer by people who have tested various methods.
I use Seafoam which will keep the gas good for a year. You are correct in storing gas without ethanol.
Depends ALOT on the ambient air moisture content. Assuming the fuel will deteriorate over time, even with stabilizer, adding new fuel will dilute not renew.
The biggest concern is that even for 5 gallon storage, *where* you store it is critical. Anything more than 5 gallons should be in a specialized container, outside of any building, and preferably in a well drained covered trench. It should have pressure venting.
When vaporized, gasoline is about as explosive as an equal mass of dynamite.
The military stores mogas in 55 gallon drums, but their turnover is quite high, so storage is typically short term.
Get two barrels so you can rotate stock
FIFO
First in first out
I think Stabil-ized fuel is good for about 12 months.
That's how you posed the question. This is the kind of question calculus addresses. I'm done with calculus. Retirement is good.
You can run the calculation though with good ol’ algebra.
1. Assume 40gal barrel, use 20gal a year and top up once per year.
2. Use 50% a year (20/40)=0.5
Year 1: 40 x 0.5 = 20 gal of original left
Year 2: 40 x 0.5 x 0.5 = 10g gal of original left
Run this as far as you want to go, it will never equal zero.
Calculus is tool to derive an equation. The derived equation is used for the calculation itself. In this example, you can eyeball the equation as Gal original left = 40gal x 0.5 to the power of the year number. This is just a button push on a scientific calculater.
As far as the stabilizer goes, read the manufacturer's instructions for usage. As far as common sense, if the manufacturer says something like a 1-year shelf life for the stabilized fuel, don't exceed that.
Keep the storage barrel or tank topped up and vented but assure a 100% turnover a few times a year. If you know a rancher or farmer, they will have the best practical advise. They always have onsite fuel storage for trucks and tractors in a volume making an off the shelf stabilizer uneconomic to use.
If storing fuel for emergency or shtf supply, avoid any partial use as much as possible and keep the tank sealed properly. Add stabilizer. Read manufacturer instructions. Call the manufacturers directly and talk to their technical service experts with your exact details and plans. Customer service is normally not competent for this kind of assistance - Ask specifically for technical service for application assistance. If you have a backup generator for example, the system manufacturer should have exact instructions for fuel storage. If a person wings it and fouls up the fuel system, that's likely an out of warranty issue at the owners cost and could completely invalidate the warranty. Your decisions.
Diesel and gasoline have different storage considerations. Both will have water issues but diesel has additional problems with sludge and bacteria contamination.
Make sure that any tanks, barrel, pumps, hoses, valves, jerry cans, vents, etc. are UL or USCG certified for the exact fuel duty. Don't want to blow yourself up. Outdoor storage is easier than vented indoor.
I once had a diesel fueled backup generator system built within a shipping container. Industrial system. I absolutely dreaded the monthly running of that system personally if my operators were unavailable. Call the alarm and power company, start the generator, manually switch power loads, etc. Several page checklist and easy to foul up and damage something, service trucks racing to the remote site and calling corporate a 1000 miles away.
I would say completely empty it and refill, at some point.
Reading the comments I agree that you should at some point, say two years, let it run down to half or lower then use it in your car and totally refill.