Generator Fuel Storage and Stabilizer

Ask anyone who services small engines what comes through the door most often after a storm, and the answer is generators that would not start. Not broken generators — generators with gummed carburetors and varnished fuel, which is a storage failure rather than a mechanical one.

What happens to stored gasoline

Two processes, both working against you. Oxidation: the lighter fractions evaporate and the rest forms gums and varnish that block the tiny passages in a carburetor. Water absorption: ethanol in modern pump gasoline is hygroscopic, so it draws moisture out of the air, and in enough quantity the ethanol-water mixture separates out and sits at the bottom of the tank, where it corrodes.

STA-BIL's listing addresses both directly: it states the product safeguards the engine and fuel system from the effects of both ethanol and non-ethanol fuels, and keeps gasoline fresh for up to 24 months in storage.

How much fuel to keep, and the honest trade-off

This is a genuine tension and anyone who tells you otherwise is not being straight with you. More stored fuel means more runtime without leaving the house. It also means more flammable liquid in your garage, more fuel to rotate, and more to go stale.

Practical approach: decide how many days of outage you are preparing for, multiply by your machine's daily consumption at your actual load, and hold that much — rotated annually. Then accept that for anything longer you will be making a trip, which is why propane and natural gas are worth considering.

Containers, and why the spout matters

Use approved fuel containers, store them outside living space, away from ignition sources and out of direct sunlight, which degrades plastic over time.

The spout is not a minor detail. You will be pouring fuel, in the dark, in bad weather, near a hot engine. A can that glugs and spills is a genuine hazard in that moment. Two designs address it: Scepter's SmartControl spout publishes a controllable flow rate with an integrated air vent, which is what stops the glugging; SureCan's design rotates a spout downward from the bottom so you never invert a full 40 lb can at all.

The short answer

Stabilizer and containers

#	Product	Best for	Score	Price
1	STA-BIL Storage Fuel Stabilizer, 32 oz The cheapest insurance against the most common generator failure: a machine that will not start because the fuel sat for a year.	Keeping stored gasoline usable	9.4/10★★★★★	$13.58
2	Scepter 5 Gallon Gas Can, SmartControl Spout The right fuel can: vented, controllable and fast, which matters because the dangerous part of a generator is usually refueling it.	Pouring without spilling	9.2/10★★★★★	$41.11
3	SureCan SureCan 5 Gallon, Rotating Spout Worth the premium if lifting and inverting a full can is awkward for you — the bottom-pour design removes the most dangerous moment in refueling.	Pouring without lifting and tilting	9.0/10★★★★★	$76.50

#ad Prices as of October 5, 2026; they may have changed since. Scores are our editorial judgment from published specifications, not test results — how we pick. How we are funded.

Propane: the answer that avoids the problem

Propane in a sealed tank does not degrade. Not in a year, not in five. No stabilizer, no rotation, no gummed carburetor, no varnish. A dual fuel generator run on propane sidesteps this entire page.

The costs are real but modest: roughly 10% less output than gasoline, and fewer BTU per gallon so you burn more volume. Against that, a tank swap is cleaner and safer than pouring gasoline, and tanks are easy to store and exchange.

If you are still choosing a machine, this is the strongest practical argument for dual fuel. If you already own a gasoline-only generator, a conversion kit may be available for your model.

Propane hardware

Running a dual fuel generator on a tank

GasSaf 10 ft Two-Stage Propane Regulator + Hose

$47.99·View on Amazon

Adding natural gas to a dual fuel unit

Generic (unbranded) Natural Gas Conversion Kit — WGen9500DF

$129.99·View on Amazon

A two-stage regulator holds output pressure steady as the tank empties, and 10 feet of hose keeps the tank well away from the hot machine. Check your generator's required inlet pressure first.

The maintenance habit that matters most

Run the generator under load for about half an hour every few months. It circulates fresh fuel through the carburetor, charges the starting battery on electric-start machines, and — most valuably — tells you the machine works while it is still convenient to find out that it does not.

Several machines help with this. WEN's fuel shutoff runs the carburetor dry before shutdown, which is the single best design feature for a machine that sits unused. DuroMax's iH series includes a battery tender to keep the starting battery charged. Champion's Intelligauge tracks hours so the maintenance schedule is something you can actually follow.

More: generator maintenance schedule.