What to do when you put in the wrong fuel

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Filling your tank with the wrong fuel is an easy to mistake to make, as I can testify from personal experience. Once, pulling into a petrol station late at night, I foolishly put unleaded into my diesel Peugeot 307’s tank. In my defence, I’d recently switched cars, and wasn’t used to picking up the diesel pump, and fortunately soon realised my error – while I still had my hand on the trigger.

Yet sudden panic set in that I’d ruined the engine and would face a hefty bill for my lapse in concentration. However, I hadn’t turned on the ignition, and had only put a tiny amount of the wrong fuel into my car. On asking the attendant, he said it should be fine - and I was lucky enough to drive off without damage. But I know I’m not alone in my mis-fuel mistake.

Potential damage

Others aren’t so fortunate, as the damage for a full-blown mis-fuelling misadventure can be significant. You see, by filling a diesel car with petrol you risk seriously damaging the engine – petrol acts as a solvent – with repairs amounting to hundreds or even thousands of pounds if the engine fails as the contaminated fuel goes through the system. Also, metal particles from the pump could be deposited in the fuel, risking further damage.

If you accidently fill your car with the wrong type of fuel but realise before setting off, tell the petrol station, as I did, and your insurer as soon as possible - and your breakdown company if you have one. If possible, put the car in neutral and ask for help to shift it to a safe spot.

Whatever you do, don’t turn on the ignition. If you only realise your error after leaving the service station you’ll find out within a few hundred yards when your car splutters to a halt.

Try to stop in as safe a place as possible, move away from the car if necessary (if you’re on a motorway hard shoulder, for example) and get in contact with your breakdown provider (or contact one for the first time if necessary). Some breakdown policies, such as the AA’s, have a dedicated roadside service called Fuel Assist, which drains, flushes and replenishes car fuel systems as you wait.

Will your insurance cover you?

If you manage to ‘mis-fuel’, thisis classed as accidental damage under a comprehensive car insurance policy. While some insurers will cover damage to your engine, others won’t – and if you breakdown you’ll need a dedicated breakdown policy to be rescued.

If they will help, the best way is for fuel sitting in the tank to be drained and the filters cleaned or replaced. This way, you protect your engine from damage. But don’t berate yourself, as hundreds of thousands of drivers have done the same in the past, and it’s not always a death knell for your engine.

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