Does fuel go off? Old fuel and fuel storage questions answered

While most will rightly drain the tank or use a fuel stabiliser, you might find yourself wanting to store fuel at home.

Here’s everything you need to know about old fuel and petrol / diesel storage.

There is always a risk when storing flammable liquid, so for the average driver, keeping fuel at home isn’t advisable.

As mentioned above, if you plan to store your vehicle for a long time, you should either drain the tank and dispose of the waste fuel properly or use fuel stabiliser.

There are rules for home storage, but you should only do so if you’re confident that you can keep it legally, safely and with the right equipment.

If you’re going to keep fuel at home, you should store it in either a plastic portable container or a metal jerry can with a tight-fitting cap. Make sure it’s sold specifically for use with petrol or diesel.

When storing petrol, remember that it is highly flammable so keep it in a secure outbuilding – like a shed or garage – that is well ventilated and away from any sources of ignition. It should be stored in as cool a place as possible but never outside. It should also be kept well out of reach of children. 

While diesel is not flammable like petrol, it can still pose a danger and should still be kept in a secure container out of the house and out of reach of any young children. 

You’re only allowed to keep a certain amount of properly-stored petrol at home at any time.

The Health and Safety Executive states that individuals are limited to storing 30 litres of petrol without a licence. However, this can only be done with certain restrictions on the type of container:

• Plastic container - storing up to 10 litres
• Metal container - storing up to 20 litres
• Demountable fuel tank - storing up to 30 litres

You will need to contact the Petroleum Enforcement Authority if you wish to keep more than 30 litres at home. 

There is no specific legal requirement on the storage of diesel in your home.

Probably not as long as you think. Once you’ve put fuel in a container you only have a few months before the quality starts to fall away – even less if the fuel is contaminated in any way.

Generally speaking, petrol has a shelf-life of six months if stored in a sealed container at 20 degrees – or just three months if kept at 30 degrees. The more it's exposed to heat, the more quickly it will go off.

If the container isn’t tightly sealed, you’ll be able to keep it for even less time and there’s increased fire risk due to flammable vapours escaping

As for diesel, it can remain usable for between six and 12 months before becoming ‘gummy’ which, if used, can clog up filters and cause you issues with your engine.

It is legal to take a plastic container or a metal jerry can to a fuel station and fill it up, although be aware that some filling stations will have certain rules about size and style of the container, so ask ahead of time if you’re unsure.

It’s recommended to place the can on the ground while filling up to avoid potential spillage which might, if large enough, lead to the forecourt being closed.

When transporting containers you should make sure it is properly secured in your vehicle to avoid leaks and potentially causing damage or injury in the event of an accident.

Within six months, it’s likely that both petrol and diesel will be fine to use although exercise some caution if it’s been left longer than that. But you are more likely to encounter problems if you have less than half a tank.

If your tank is full of old fuel (especially old diesel) have it drained by a garage or a professional mobile service.

If you suspect your petrol or diesel is stale the best advice is to try topping up with fresh fuel from a filling station.

Possibly, although that largely depends on what the fuel is and how old it is. 

If you use old petrol, you may suffer poor starting and, or loss of performance. You’ll probably be able be able to overcome this by filling up with fresh petrol.

However, if oxidisation of the petrol has occurred, it could cause deposits and other impurities to clog up the inner mechanisms in your engine, and lead to substantial damage.

With diesel, decomposition can cause the fuel filter and parts of the fuel injection system to become blocked which could see you facing a hefty repair bill.

Fuel stabilisers are intended to extend the shelf life of both petrol and diesel. When using a stabiliser, make sure it’s suitable for the fuel you’re using and always ensure you follow the instructions on the label. 

While these are available to purchase the RAC does not normally recommend their use.

If you’ve got an issue with your fuel and want to get your car checked out by a professional, it’s always best to visit a garage.  

Consider using a mechanic you can trust, or explore the RAC Approved Garage Network, which only includes garages that provide quality work and exceptional customer service, giving you peace of mind if your car needs attention.