INTRODUCTION
Petrol is a mixture of many components with different properties that contribute to the
performance of the fuel. When petrol is left out in an open container exposed to the air it will
in time completely evaporate. As it evaporates the composition and properties will change
because different components evaporate at different rates. This is a normal feature of petrol
and the same process takes place in equipment fuel tanks. Where petrol is kept for more
than a week in equipment tanks then it can become stale and it is better to add fresh fuel
before using. Examples are classic, veteran and vintage cars and bikes, racing cars and bikes,
drag cars, boats, dual fuel vehicles, lawn mowers etc.
Generally petrol will last in equipment fuel tanks for about 3 weeks at a temperature of
around 20 deg C, after that it will perform better when fresh petrol is added.
Petrol will last in sealed containers for more than 6 months, while some breathing will take
place this is not enough to significantly affect product quality.
In underground storage tanks the rate of replenishment prevents the fuel from becoming
stale.
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