Unleaded petrol 95, 98 and 100 octane
If you have filled the tank with unleaded petrol of different octane than what you usually use, then there is nothing to worry about. Just wait until the next filling to use the fuel of your choice.
Diesel in a petrol vehicle
If you have been unlucky enough to put diesel in a petrol vehicle, you’ll be relieved to know that there is usually no serious damage done to your engine. Unlike diesel, which has to be compressed to ignite, petrol is ignited by a spark generated by the spark plugs. As soon as the car is switched on, the diesel will clog up the spark plugs and fuel system, causing the vehicle to misfire, smoke and possibly stop running. After the contaminated fuel has been flushed from the system, the car should start fairly quickly. You will initially see smoke whilst the diesel residue is burnt off, and then the vehicle should run as before the incident.
Signs of diesel in a petrol car
- Engine misfiring
- Engine won’t start
- Engine cuts out
- Smoky exhaust when drivingς
Two litres of diesel or less
We recommend a full drain for any amount of contamination, but if you have put in 2 litres or less of diesel in a petrol car (less than 5% of a full tank) and then fill up your remaining tank with petrol, there should be no damage caused to your vehicle.
More than two litres of diesel (5%+)
DO NOT START YOUR ENGINE. Push your vehicle to a safe place and give us a call to drain and flush your fuel tank. Once this has been carried out, fill up your tank and there should be no damage caused to your vehicle.
Petrol in a diesel vehicle
With modern diesel fuel pumps running at such high pressures, petrol in a diesel car may reduce the lubrication in the pump, causing damage to the pump when the metal components rub together. The petrol may damage the diesel pump & fuel system seals. The level of the damage depends on how long the engine was running after the misfuelling.
This rubbing together in the pump can cause metal particles to be deposited into the fuel and these may be carried up to the fuel system. The further the petrol moves in the fuel system, the more difficult and costly the repair will be. So, if you have already started driving, as soon as you realise that you have contaminated your diesel with petrol STOP DRIVING and SWITCH OFF!
Signs of petrol in a diesel car
- Vehicle is difficult to start, especially when warm
- Engine gets noisy under load
- Smoky exhaust when driving
5litres of petrol or less
We recommend a full drain on any amount of contamination. If you have fueled with 5 litres or less of petrol (less than 10% of your tanks capacity) and then top up with diesel to a full tank, your vehicle should be able to burn off any contamination.
More than five litres of petrol
DO NOT START YOUR ENGINE or put your key in the ignition as this can prime the electric pump in the tank and circulate the contaminated diesel. It is essential to carry out a full drain. Once the contaminated fuel has been removed and the tank is filled with the correct diesel there should be no damage to the engine.