Technical Check For Water In Your Petrol

Petrol in tanks, whether for your yacht or tender, can go off. Ken Endean suggests an annual precaution

- Ken Endean

For many years, we have been advised that petrol in storage may ‘become stale’, and that if engines are unused for long periods their tanks should be drained. One problem affecting modern petrol/ ethanol blends is that the ethanol absorbs water from the air and eventually the water/ethanol mix undergoes phase separation. Recently the introduction of petrol blends with higher concentrations of ethanol has prompted more warnings, including that petrol should not be stored in a container for longer than a month. I may, inadvertently, have been carrying out a longterm scientific experiment, because my boat’s main petrol tank has not been drained for 35 years and yet the engine runs smoothly.