What To Do If You Fill Up With The Wrong Fuel

Have you recently refuelled with petrol instead of diesel, or vice versa? Fear not. ‘Misfuelling’ is a very common mishap by motorists, which you can (in most cases) easily fix by following the steps in this article.

1. If you filled up with less than 10% of the wrong fuel, you don’t have to read any further. In most cases you will be able to top up with the correct fuel straight-away and drive off. This is because – if you put petrol into a diesel car – the petrol will float on the top for a while.

Tip: Continue to fill up with a high lubricity diesel like Shell V-Power Nitro Plus and don’t let your car get half-empty for 2,000 miles. This will gradually dissolve the petrol until it’s no longer an issue. But if in doubt, contact the manufacturer of your vehicle.

If you have misfuelled by over 10%, follow the steps below.

2. The number most important rule is to not turn on the ignition or start the car. The electric pump in your car usually starts to intake fuel as soon as the ignition is turned on, which will allow the wrong fuel to contaminate your engine a lot quicker.
3. Inform workers at the fuel station that you have put the wrong fuel in your car, then seek help with moving the car out of the way. It’s important not to obstruct any traffic while you are distracted.
4. Call an expert who can drain the unwanted fuel, clean the filter and pump and refuel your car correctly. The AA offers a roadside service called ‘Fuel Assistant’, and Fuel Doctor are UK-wide specialists in this kind of slip-up.

It’s more common to add petrol instead of diesel than it is to add diesel instead of petrol, simply because the diesel nozzle is bigger. But either way, a misfuelling specialist should have your car up and running again in no time; saving you time, money and a lot of aggravation.

1. This is more of an awkward situation, but try to stop your car in a safe place away from main traffic. If you are on the motorway, the hard shoulder would be ideal. It’s also best to step out of the car in case of a collision.
2. Call a breakdown provider such as the AA. You will kill two birds with one stone here because they can drain and refuel your car then give you a lift if necessary.
3. If there is severe damage to your fuel tank due to using the wrong fuel, contact your insurance provider to check if you’re covered. If you have a comprehensive insurance policy, misfuelling should be covered as ‘accidental damage’.

Metal damage to the pump – Diesel pumps transport fuel to the engine at high pressure, meaning that diesel has to have high lubricity. Petrol acts as a solvent, which reduces lubrication and causes abrasive, metal-to-metal contact in the pump. This alone causes damage, but metal particles can also come loose and damage the whole fuel system.

The wrong fuel contaminating the whole system – If the unwanted fuel travels too far into your vehicle’s system, it can cause irreversible damage. In this instance it’s often cheaper to have the engine replaced!

Common Rail system problems – if you have a Common Rail (or HDi) system in your diesel car and it gets contaminated, the low and high pressure fuel pumps, injectors, fuel rail, line filters and fuel tank might all need replacing.

Gasoline Direct Injection engine problems – If you managed to get diesel into a petrol vehicle, GDI engines are especially sensitive to damage.