Does Fuel Go Off? The UK Prepper’s Guide to Safe Storage and Longevity

Fuel is one of those essentials every UKSN member quickly learns is more complicated than it first appears. Whether it’s powering your generator during a blackout, keeping your camper van moving across the countryside, or fuelling a stove on a weekend camp, knowing how long it lasts and how to store it properly is crucial.

So, does fuel actually go off? The answer is yes, but the story behind why, how, and what to do about it is a little more interesting.

Understanding Fuel Longevity

Different fuels degrade at different rates, and knowing these timelines can save you frustration, wasted money, and potentially a lot of engine trouble. Petrol, for example, tends to last between three and six months when stored correctly. Diesel fares slightly better, often lasting up to a year, but is prone to bacterial growth if water contaminates it. Kerosene is comparatively stable and can remain usable for one to two years in a sealed container.

One important point for UK preppers is that not all petrol is created equal. Most modern petrol is ethanol-blended:

• E10 petrol – Contains up to 10% ethanol and is common in most UK filling stations. Ethanol attracts water and can accelerate fuel degradation, making it less suitable for long-term storage.

• E5 petrol – Contains up to 5% ethanol and is still available in some stations. It is slightly more storage-friendly than E10.

• E0 / ethanol-free petrol – Rare, but ideal for long-term storage because it doesn’t attract water and is less prone to oxidation.

Diesel is different. Standard UK diesel doesn’t contain ethanol, though small amounts of biodiesel may be present. Kerosene, too, is generally free from ethanol, making both fuels more stable for longer storage.

Why Fuel Goes Off

Fuel degrades for a few key reasons. Petrol oxidises, forming gums and varnishes that can clog engines. Diesel can develop microbial growth, often called “diesel bug,” which feeds on hydrocarbons and can ruin a tank if left unchecked. Even kerosene, while more stable, will deteriorate if stored in hot, bright conditions or left exposed to air.

Water contamination is another common issue. Even small amounts can lead to separation in petrol, bacterial growth in diesel, or reduced efficiency across the board. Temperature extremes, whether freezing winter garages or hot summer sheds, further accelerate the chemical breakdown.

Storing Fuel Properly

For UK preppers, how fuel is stored is just as important as how it’s used. Containers should be appropriate for the fuel type, sealed tightly, and kept somewhere cool and dark. Metal or high-quality plastic jerrycans with secure caps are ideal, and wherever possible, store them away from direct sunlight and heat sources.

Labelling containers with the fuel type and purchase date is another simple step that makes rotation easier. Using older fuel first ensures you never rely on something that has degraded beyond usability.

Stabilising Fuel for Long-Term Storage

If you plan to store fuel for months or even years, a few strategies can help. Fuel stabilisers slow oxidation and prevent gum formation in petrol and diesel, keeping them usable for longer. Keeping containers as full as possible reduces the amount of air that can accelerate breakdown, while regular stock rotation ensures your reserves are always fresh.

For ethanol-blended petrol, long-term storage is always more challenging. E10, for example, will degrade faster than E5 or ethanol-free petrol, so it’s best to use it quickly or add a stabiliser specifically designed for ethanol blends.

Practical Uses at UKSN Camps

Fuel isn’t just about emergencies. At UKSN camps, stored fuel can power generators for lighting or charging devices, keep vehicles moving across remote locations, or fuel stoves and heaters. Reliable fuel can be the difference between a smooth, enjoyable trip and one that requires last-minute improvisation.

By understanding how fuel behaves, storing it correctly, and taking steps to stabilise it, UKSN members can ensure their adventures and emergency plans run smoothly.

Spotting Fuel Problems

Even well-stored fuel should be checked before use. Diesel may develop a sludge layer at the bottom of a tank, while petrol may darken or smell unusual over time. If you notice these signs, filter or replace the fuel before adding it to engines or stoves. This simple precaution prevents damage and keeps your equipment running reliably.

Conclusion: Keep Your Fuel Reliable

Fuel may go off over time, but with proper storage, careful rotation, and the occasional stabiliser, it can remain a dependable resource.

Understanding the differences between petrol types, diesel, and kerosene - and being aware of ethanol content helps ensure your fuel lasts longer and performs when you need it most.

Whether you’re running a generator at a UKSN camp, keeping a vehicle ready for 4X4 adventures, or simply building an emergency reserve, fuel you can trust is just as essential as any other piece of kit in your prepper arsenal. Take the time to store it correctly, inspect it before use, and rotate your stock, and you’ll have one less thing to worry about!