How long petrol and diesel last in a can, and how to store them without creating a hazard.
Fuel degrades, and stored fuel is both a fire risk and a regulated one. Confirm the quantity and licensing rules for your own jurisdiction; this is general guidance, not a compliance ruling.
Quick answer: How long can you store petrol in a jerry can?
At least a year in a closed can kept cool, by Chevron’s figure; add a stabiliser at fill if the can sits in direct sun or above 30 °C. Small-engine makers set shorter limits: STIHL tells owners to use pump petrol within 60 days, and within 30 where possible. Keep the can full, sealed, cool and dark.
As a rough guide, petrol in a full can kept closed and cool keeps its quality for about a year, while engine makers set 30 to 60 days for fuel bought for a small engine. Diesel keeps up to about a year in clean, dry storage, and Chevron treats a year or more as prolonged storage that calls for a stabiliser. Kerosene stores longer still. Heat, air and water all shorten these times, so a full, sealed can in a cool dark place lasts longest.
Petrol degrades by oxidation. It is a blend of light hydrocarbons, and the lightest fractions evaporate first while the rest react with dissolved oxygen to form gums and varnishes. The fuel goes darker, smells sour and leaves a lacquer in carburettor jets and injectors. Nothing about that is reversible, which is why a stabiliser goes into fresh fuel and does nothing for old.
Diesel fails by a different route and on a longer clock. It oxidises slowly, but its real enemy is water, which arrives by condensation in the headspace as the container breathes through the day. Water settles under the fuel and the interface between the two is where microbial growth lives, the sludge the trade calls diesel bug. That growth blocks filters and is why a diesel store is kept full, sealed and drained of any water bottom rather than simply kept cool.
The storage rules follow from the chemistry. Full limits the oxygen and the condensing surface. Sealed keeps water vapour out. Cool halves the reaction rate for every ten degrees you take off. Dark keeps ultraviolet out of the equation entirely. Do all four and the figures above are conservative; skip one and they are optimistic.
Petrol blended with ethanol, at E10 and above, holds far more water than ethanol-free petrol and can phase-separate once liquid water gets in, leaving water and ethanol at the bottom of the can. It also attacks some seals and coatings. For longer storage, use ethanol-free fuel where available, or a stabiliser rated for ethanol blends, and confirm the container is rated for the blend.
Phase separation is worth recognising because it is irreversible and looks like nothing at all until the can is disturbed. Water in the blend stays in solution up to a point and then drops out, taking most of the ethanol with it into a distinct layer at the bottom. The petrol above is now low on octane and the layer below is not fuel. Stirring does not recombine them, so a can that has separated is a disposal question rather than a treatment one.
Petrol in a tightly closed container kept in a cool place retains its quality for at least a year, according to Chevron’s Motor Gasolines Technical Review. One engine maker sets a far shorter limit: STIHL tells owners not to store or use pump petrol older than 60 days, and preferably 30, even with a stabiliser. Directive 98/70/EC and the standards it calls up, EN 228 for petrol and EN 590 for diesel, set limits for fuel as it is sold, with no storage life, so every figure, the rough guide above included, depends on how the fuel is kept.
| Fuel and storage | What the source says | Source |
|---|---|---|
| Petrol in a closed container, kept cool | Keeps its quality for at least 12 months; fill to about 95% | Chevron, Motor Gasolines Technical Review |
| Petrol in direct sun or above 30 °C | Add a stabiliser when you fill the container | Chevron, Motor Gasolines Technical Review |
| Two-stroke mix, stored the same way | Keeps as well as petrol | Chevron, Motor Gasolines Technical Review |
| Pump petrol or mix bought for small engines | Do not store or use it past 60 days, preferably 30, even stabilised | STIHL fuel FAQ |
| US B20 diesel blend at its specification minimum | Up to 12 months in clean, dry storage | NREL Biodiesel Handling and Use Guide |
| Diesel kept a year or longer | Prolonged storage: add a stabiliser with antioxidant, biocide and corrosion inhibitor | Chevron, Diesel Fuels Technical Review |
The gap comes from what each source protects. Chevron’s year describes the fuel, kept in a closed container with little air in it and kept cool. An engine maker protects a small carburettor, and American Honda notes that fuel in the float bowl deteriorates faster than fuel in the tank because the volume is small, it sits near engine heat and it is open to the air. Honda also warns that air in a part-filled tank speeds deterioration. For fuel going into a small engine, follow that engine maker’s limit. For a sealed, full can in a cool store, Chevron’s year is the published figure.
Ethanol’s effect is on water. Chevron puts the water ethanol-free petrol dissolves at up to 150 ppm at 21 °C and E10 at 6,000 to 7,000 ppm. Past that limit, or as the blend cools, water drops out with the ethanol, and up to 90% of the ethanol can leave the petrol, lowering its octane. The US EPA found that humid air alone rarely gets there: at 38 °C and 100% relative humidity it would take well over 200 days to saturate petrol in an open can. Liquid water does it, from rain, a splash or condensation in a can that breathes as the temperature swings, which is why the closure matters (see venting and pressure).
EN 590 diesel may contain up to 7% FAME, the biodiesel component, by volume (Directive 98/70/EC, Annex II). We found no published storage figure for that B7 blend. The nearest is NREL’s for US B20: a blend that only just meets its specification should keep for up to a year in clean, dry storage, and the most stable blends showed little or no change after ageing equivalent to three years. Red diesel is gas oil with fiscal markers and red dye added (Hydrocarbon Oil (Marking) Regulations 2002, regulation 3), and it meets the same water and microbial-growth problems in store as any diesel; the tax side is in red diesel rules. Our generator fuel guide covers draining water from a standby store.
A fuel stabiliser slows oxidation and can extend usable life to a year or more. It does not reverse degradation, so add it to fresh fuel, not old. Follow the dose on the product.
A stabiliser slows oxidation and does nothing about water, so it will not help a container that breathes moist air, and it does not address ethanol's tendency to draw water in. Nor does it recover fuel that has already gummed. A stabiliser buys time on fuel that is fresh, dry and sealed, so it works alongside the storage discipline.
For stored petrol the additive is a stabiliser, an antioxidant. An injector or system cleaner is a detergent for deposits already in an engine, and a biocide kills the microbial growth that lives in diesel with water under it. Chevron describes the antioxidants as aromatic amines and hindered phenols that stop petrol reacting with oxygen to form peroxides and gums, and says virtually all petrol needs them, so pump petrol normally carries some and a storage stabiliser adds more. The cleaners, which Chevron calls deposit-control additives, go into the fuel tank to clean intake and combustion-chamber deposits.
Stabilisers differ by fuel. The safety data sheet for one petrol storage stabiliser says not to use it in diesel. For diesel kept a year or more, Chevron’s Diesel Fuels Technical Review recommends a stabiliser containing an antioxidant, a biocide and a corrosion inhibitor, and says additives work best when added immediately after the fuel is made. NREL makes the same point for biodiesel blends: antioxidants prevent ageing and cannot correct fuel that has already degraded. For E10, the control is keeping liquid water out, as the US EPA findings above show.
Add the stabiliser as you fill the can with fresh fuel, at the dose on the label. American Honda’s generator guidance tells owners to treat every fill of a portable fuel container, because nobody knows how long that fuel will wait, and to run a machine outdoors for 10 minutes the first time so treated fuel reaches the whole fuel system. Then rotate on the fill date: write it on the can, use the oldest can first and refill it with fresh, treated fuel to its marked capacity, as set out in how to use a jerry can. Honda relays US EPA advice that stabilised fuel which has sat 12 months in a portable container can go into a car whose tank is fairly full.
Rotation depends on a can that stays sealed between uses. Steel holds petrol’s light ends in, and plastic needs a barrier such as fluorination to do the same, compared in steel vs HDPE fuel cans. Size the store to what you can rotate. A home in Great Britain may keep up to 30 litres of petrol without notifying anyone (UK petrol container rules), and a workplace store falls under the DSEAR risk assessment described in DSEAR and ATEX for fuel stores.
A fire around stored fuel rarely starts in the liquid. Petrol gives off vapour that is heavier than air, so it sinks, pools along the floor and travels until it reaches an ignition source across the room. Pouring fuel builds a static charge, and one spark will light that vapour. Keep the nozzle touching the container as you transfer, so any charge bonds and drains instead of jumping a gap. Never fill a can in the back of a vehicle or on a plastic liner: the insulated surface lets static build with nowhere to go. Set the can on the ground and fill it there.
Petrol has a flash point around −40 °C, so it gives off ignitable vapour at any temperature you will ever store it at. Diesel's flash point is above 55 °C, so at ambient it does not. That single figure is why a petrol store is a fire compartment question and a diesel store is largely a pollution one.
Petrol vapour ignites between roughly 1.4 and 7.6 per cent by volume in air. Below that it is too lean and above it too rich. That makes a nearly empty container the most dangerous one: a full can has a headspace too rich to burn, and a drained can sits right in the middle of the range. An empty fuel can is not a safe fuel can, and it is the one people carry into a workshop.
The vapour is also three to four times denser than air, so it does not disperse upward the way intuition suggests. It runs downhill along a floor, pools in a pit or an inspection channel and finds a pilot light or a switch several metres away. That is the whole argument for ventilation at low level and for keeping a store away from anything with a flame or a spark in it.
A UN-marked, fuel-rated can is designed and tested to hold fuel; a random jug or reused bottle is not. In some markets the can itself must meet emissions rules on permeation and spouts, covered in EPA and CARB compliance.
Filling nearly full does a job: less air means less oxygen to oxidise the fuel and less room for moisture to condense as the temperature swings. The tension is expansion. Fuel swells as it warms, so a can brimmed on a cool morning can bulge or weep by the afternoon. Leave a small gap for that movement. A vented cap manages the pressure and temperature swings for you, letting the can breathe rather than deform or force fuel past the seal. See venting and pressure.
Mark the fill line rather than judging it, because the right level is not obvious by eye and gets rushed at the pump. Around ninety-five per cent full is the target on a fuel can: enough to limit the oxygen and the condensing surface, with enough space left for the fuel to expand into on a hot day. A can filled to the neck is the failure case, and it is the one a helpful attendant produces.
Three habits cause most of the trouble. Storing petrol in an attached garage puts its vapour near water heaters and other ignition sources, so a detached, ventilated space is safer. Topping up old fuel with fresh dilutes the fresh and does nothing for the old, dragging the whole can down to its weakest part. And sealing fuel in a rigid, non-vented container lets it swell and deform in heat, then draw a vacuum and collapse as it cools. Keep old and new stock separate, and match the container to the fuel.
Dating is the discipline that makes the rest work, and it costs a marker pen. A can with its fill date on it can be rotated, judged and retired on evidence; a can without one is judged on memory, and memory always concludes the fuel is newer than it is. Write the date on the can rather than on a list, because the list and the can get separated and the can is what somebody picks up.
Most jurisdictions cap how much fuel you may store without a licence, and set rules on container type and location. In Singapore, storage of petroleum and flammable materials is licensed by the Civil Defence Force. Check your local limit before you stockpile.
For Great Britain the figures are published. Petrol at home, and at other premises that are not a workplace, is capped at 30 litres before you must notify the local Petroleum Enforcement Authority, a notice you renew every January. A licence is required above 275 litres, and the container itself is limited to 10 litres in plastic and 20 litres in metal. A workplace that stores petrol but does not dispense it falls under DSEAR instead, with no fixed quantity. Northern Ireland sets lower domestic limits: two metal containers of up to 10 litres, or two plastic containers of up to 5 litres. Diesel sits outside those size rules. Our UK petrol container regulations guide works through what each threshold obliges you to do.
A separate regime covers the environmental side. The Control of Pollution (Oil Storage) (England) Regulations 2001 apply to oil stored outside a building in any container of more than 200 litres, and the definition of oil includes petrol. The threshold is per container, so a store of 20-litre cans sits outside them however many cans it holds, while drums, IBCs, bowsers and tanks are in. Homes are covered only above 3,500 litres, and farms follow separate agricultural fuel rules. Where the regulations apply the requirement is secondary containment, and our spill containment guide carries the sizing arithmetic.
Workplace storage brings a third layer. In Great Britain, DSEAR requires an employer to assess the risk from a dangerous substance, control ignition sources and classify hazardous areas where an explosive atmosphere may occur. The EU equivalent runs through the ATEX workplace directive, with equipment covered separately. None of that changes the container you buy. All of it changes where you may put it and what may be switched on nearby.
Fuel-rated, vented and labelled. We make these for the job.
| Your use case | Recommended can | Why this one |
|---|---|---|
| General fuel storage |  20L NATO Steel Fuel Can |
Coated steel, UN-marked, with a vented cap. |
| A plastic fuel can |  Fluorinated HDPE Jerrycan |
Fluorinated HDPE to control permeation. |
| Light fuel storage |  20L Aluminium NATO Can |
Aluminium where weight matters more than cost. |
| US-market fire safety |  Flame Mitigation Devices |
A flame arrestor for markets that require one. |
| US consumer sale |  Child-Resistant Closures |
A child-resistant cap to the CPSC pattern. |
At least a year in a tightly closed can kept cool, by Chevron’s Motor Gasolines Technical Review, which adds a stabiliser at fill where the can will sit in direct sun or above 30 °C much of the time. Engine makers are stricter for fuel bought for small engines: STIHL says not to store or use pump petrol older than 60 days, and preferably 30. A part-full or vented can ages faster, so store it full, sealed, cool and dark, and rotate.
Ethanol changes what water does to petrol. E10 dissolves 6,000 to 7,000 ppm of water at 21 °C, against 150 ppm for ethanol-free petrol, by Chevron’s figures. Past that limit, or as the fuel cools, water drops out and takes up to 90% of the ethanol with it, leaving low-octane petrol over a layer an engine will not run on. The US EPA found humid air alone rarely does this; liquid water from condensation, rain or a splash does.
Cool, shaded, ventilated, away from any ignition source and away from living space. Heat drives the pressure cycling that stresses seals and vents vapour. Keep quantities within the limits your local fire code sets for a domestic or workplace store, which are usually well below what people assume.
Full. A full can has little air space, so there is less oxygen to oxidise the fuel and less room for condensation to form as temperature swings. A part-full can degrades its own contents faster and corrodes from the inside at the fuel line.
Yes. American Honda’s generator guidance says every stabiliser has a shelf life and its performance deteriorates over time, so an old bottle protects less fuel than a fresh one. Write the opening date on the bottle, keep it closed in a cool store and use it within the period on its label. Treated fuel ages too: Honda warns that even stabilised petrol left in an engine can deteriorate in long storage.
It burns, and some products are flammable liquids in law. Three stabiliser safety data sheets we checked give flash points of 46 °C, above 60.8 °C and 79.4 °C, and GB CLP classes a liquid flashing at 60 °C or below as flammable. All three are aspiration hazards if swallowed. Store it like a fuel product, away from heat and out of reach of children. Once it is dosed into petrol, the can holds petrol and burns like petrol.
Engine makers recommend it rather than warn against it: American Honda tells generator owners to add stabiliser to every fill of a fuel can, and Chevron advises it for petrol stored in sun or heat. Use the right product at the label dose, a petrol stabiliser in petrol and a diesel product in diesel; one petrol stabiliser’s safety data sheet says not to use it in diesel. It cannot revive stale fuel, so add it fresh, and check your engine manual for any additive its maker rules out.
Only if fuel stays in the machine or the can through the winter. American Honda’s generator guidance shows the usual pattern: for one to two months, fill the tank with fresh, stabilised fuel; for two to twelve months, drain the carburettor; beyond a year, drain the tank and the carburettor. STIHL tells owners to store its tools dry if they will stand unused for more than 30 days. For a mower, motorcycle or snow blower, follow its own manual first.
In the UK, E5: the super grade of 97 octane or more, which holds no more than 5% ethanol and remains on sale at filling stations that sell two grades of petrol, according to the Department for Transport’s E10 guidance. The same guidance lists boats and petrol garden machinery such as mowers and chainsaws among equipment that may not suit E10, so check the manual. A vehicle approved for E10 can mix E5 and E10 in the same tank.
Petrol left in a boat over winter is best treated when you fill and kept in a full tank. The US EPA’s advice for any long storage is a full tank, to prevent condensation, with a stabiliser considered. Chevron advises extra care with ethanol blends in boat engines, because water separates them, and the UK’s E10 guidance lists boats among engines that may not suit E10. Keep rain and spray out of the vents, and check the engine manual for its approved fuel.
Yes, in a fuel-rated can, and a detached, ventilated garage or shed beats an attached one, where vapour sits near the house and its ignition sources. In Great Britain the Petroleum (Consolidation) Regulations 2014 let a home keep up to 30 litres in a store that is not living accommodation, has a direct exit to the open air, is ventilated to it and is kept free of ignition sources. An attached store must be fire-separated from the house. Outdoors, keep cans in shade.
No. A stabiliser slows the oxidation that turns fresh petrol into gum and varnish, and can stretch its usable life to a year or more, but it cannot reverse damage already done. Add it to fresh fuel as you fill the can. It does nothing about water, so it will not rescue an ethanol blend that has phase-separated. Use it alongside a full, sealed, cool and dark store.
Yes, if its petrol will wait for an outage. American Honda tells owners to add stabiliser to every fill of a fuel can, because nobody knows how long that fuel will wait, and fuel in a carburettor ages faster than fuel in a sealed can. Choose a stabiliser rated for ethanol blends, dose it into fresh fuel and store the can full, sealed, cool and dark. Diesel for a generator lasts longer, and water is its main threat.
Let the can stand so the water settles to the bottom, under the diesel. Pour or pump the diesel off the top into a clean can, stop short of the water layer, and treat the water and the last of the fuel as waste. Slime at the boundary is diesel bug, the microbial growth that blocks filters. Water gets in by condensation in the headspace, so store diesel full, sealed and drained of any water bottom.
Yes, for oxidation. A stabiliser is an antioxidant, and Chevron says such inhibitors stop petrol reacting with oxygen to form peroxides and gums. It does nothing about water. Once liquid water gets into an ethanol blend, the fuel can separate into a water-ethanol layer, and a stabiliser does not reverse that. Add the stabiliser to fresh fuel and keep the can full and sealed, so little air and moisture sit above the fuel.
Yes, though far less readily than petrol. Diesel's flash point is above 55 °C, so at normal storage temperatures it gives off too little vapour for a spark to light, while petrol flashes at around minus 40 °C. Heat and spray change that. HSE counts high flashpoint liquids at elevated temperatures as dangerous substances, and DSEAR requires area classification where oil mists can form, diesel among them. For transport diesel is a Class 3 flammable liquid, UN 1202, packing group III.
Up to about a year in clean, dry storage, by NREL's figure for a US biodiesel blend, and longer if the can is kept cool and sealed and the fuel is treated. Chevron treats a year or more as prolonged storage that calls for a stabiliser. Diesel oxidises slowly. Its real enemy is water, which condenses in the headspace as the can breathes, settles under the fuel and feeds the microbial growth the trade calls diesel bug, which blocks filters. Store the can full and sealed, and drain off any water bottom before you use the fuel.
Stand the can on the ground and fill it there, never in the back of a vehicle or on a plastic liner, where static builds with nowhere to go. Keep the nozzle touching the can as you fill so any charge drains away instead of sparking. Stop at the can's marked capacity, which leaves about a tenth of the can as air space for the fuel to expand on a warm day, then close the cap. A can filled to the neck bulges or weeps by the afternoon.
Store a filled jerry can upright, with the closure on top. On its side the fuel sits against the closure, so a gasket that has hardened or taken a compression set weeps, and a vented cap can pass liquid instead of vapour. Upright, the seal carries no load and the headspace stays at the neck. Horizontal cans are the exception: they are built to lie flat, so store each can the way it was designed to stand.
It slows the oxidation that turns stored fuel into gum and varnish, which can stretch the usable life of petrol to a year or more. It works on fresh fuel only: it cannot reverse degradation, and it does nothing about water, so it will not save fuel in a can that breathes moist air or an ethanol blend that has separated. Add it when you fill, follow the dose on the product, and keep the can full, sealed, cool and dark.
Kerosene is the most stable of the common fuels. No standard sets a storage life for any of them. Petrol in a tightly closed can kept cool keeps its quality for at least a year by Chevron's figure, though small-engine makers such as STIHL set 30 to 60 days. A US biodiesel blend at its specification minimum keeps up to a year in clean, dry storage (NREL), and water, not age, usually spoils diesel. Whatever the fuel, a full, sealed can kept cool and dark lasts longest.
Slowly, and far less than petrol. Diesel has a flash point above 55 °C, so at normal storage temperatures it gives off too little vapour to ignite, while petrol flashes at around minus 40 °C and loses its lightest fractions to evaporation in storage. A sealed diesel can loses little. Diesel fails in storage through water and the microbial growth that lives where water meets the fuel.
No. A fuel stabiliser slows the oxidation that turns fuel to gum and varnish, and it does nothing about water that condenses in a can or separates out of an ethanol blend. Water settles under the fuel, where diesel bug grows at the interface, and petrol that has phase-separated needs disposal rather than treatment. Keep water out instead: store the can full, sealed, cool and dark, and add stabiliser to fresh fuel only.
The standards and regulations this page relies on, at their issuing body. Where a market rule is named here, check the current revision before you specify against it.
Last reviewed by David Guru, Co-Founder & Business Development Director.
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