Storing petrol over winter

Posted on December 8th, 2021 by GEM Motoring Assist

By this time of year, many people cease using certain petrol-powered machinery, until better weather arrives. These vary from classic (or cherished) motorcars to lawnmowers.

Why does E10 fuel last less time in storage?

While petrol has never been everlasting, the arrival of E10 unleaded from September means that ‘standard’ fuel lasts even less time in storage. As E10 contains a higher proportion of ethanol than pre-September blends of 95RON, it has a reduced ‘shelf-life’. This is due not only to increased rates of oxidisation, when the fuel comes into contact with air, but also the ethanol’s tendency to absorb moisture. This humidity originates from condensation that forms in the airspace above the fuel within the tank. Therefore, the fuller the fuel tank, the less air is present, meaning fewer water droplets form as the temperature changes.

How to store petrol

Should you be storing either a vehicle, or other petrol-powered machinery, we recommend super-unleaded petrol, which contains only up to 5% ethanol rather than up to 10%. In addition, fill the tank so that you minimise the quantity of air trapped inside. Yet, be wary that overfilling can pose a fire risk. You might consider a fuel additive but they do not have to meet any established technical standard. Buy from a respected brand but look for a product that is more of a fuel stabiliser, rather than one that boasts that it solves all ethanol-associated issues but cannot substantiate its claims.