PETROL IN DIESEL CARS
Due to the increase of diesel-fuelled cars, it’s increasingly common for people to forget they’re running a diesel engine and misfuel with petrol.
Diesel fuel pumps operate at very high tolerances, with the diesel acting as a lubricant. Unfortunately, petrol has a solvent effect, reducing lubrication and damaging the pump.
This causes metal-to-metal contact, potentially distributing metal particles from the damaged pump throughout the fuel system. Furthermore, the compounds found in petrol can damage seals within the fuel system.
THE MOST VULNERABLE ENGINES
If your vehicle operates an HDi diesel engine, you’re most at risk of damage from misfuelling. These common-rail, direct fuel injection systems operate at very high pressure and run via high and low-pressure pumps.
Once diesel reaches this system, it may be necessary to replace the high and low fuel pumps, the injectors, the fuel rail, the line filters, and the fuel tank. The same applies to Gasoline Direct Injection (GDI) engines, which run on the same principles as an HDi engine, albeit with petrol.
DON’T START YOUR CAR
As soon as you start your engine, fuel is drawn into the system and this is when damage occurs. Not starting the car in the first place is the quickest way to avoid such damage. Ignore this at your peril, as driving a misfuelled car can result in a sudden loss of power.
In this case, pull over to the nearest safe area and call the AA or a similar breakdown service. Whatever you do, don’t try and keep driving.
WORK OUT HOW MUCH FUEL YOU PUT IN
All going well you’ll realise you’re misfuelling straight away and will be able to stop any problems before they arise. As a rule, if you’ve filled less than 10% of the tank with the wrong fuel, you should be able to top up with the correct fuel and continue your journey.
If you’ve pumped in more than 10% of the wrong fuel or are unsure as to how much you’ve pumped in, you’ll need to organise to have your tank drained.
CALL THE PROFESSIONALS
Unless you’re a good mechanic, draining the wrong fuel should be left to the experts. If there isn’t much fuel, your breakdown service should be able to do it wherever you are. Unfortunately, if you’ve added a lot of the wrong fuel, you’re likely to need the help of a garage. They’ll be able to get you back on the road quickly and undo any damage that may have been done.
THE WORST CASE SCENARIO
It’s not unknown for people to be aware they’ve misfuelled, but drive on regardless. This is the worst thing you can do, as the further the wrong fuel enters the system, the worse the damage.
Even if your vehicle isn’t an HDi or GDI vehicle, if the damage is widespread it may be cheaper to replace the entire engine than to fix the damaged parts.
REDUCING THE RISK OF MISFUELLING
Misfuelling only takes a moment’s distraction, so pay attention if you’ve bought a new car or are using a different one. You’re also more likely to misfuel in an unfamiliar petrol station, or if you’ve started using a different fuel brand.
When fuelling up, don’t allow yourself to be distracted by other people including your passengers. Finally, never assume hose colours are the same, as they can be different at various petrol stations or change without warning.
Misfuelling is a costly mistake that is easily avoided. Simply pay the same level of attention at the petrol station that you do when you’re on the road, and if you do misfuel, don’t let the problem escalate.