Kilsby: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — provided no one has started it. Everyone in Kilsby starts with "have I ruined it?", and the fair answer is usually no: petrol resting inside your tank of a diesel stays harmless till priming, cranking or driving draws it into your fuel system. Petrol in Diesel is who to phone, with your motor left off, and so it stays that way. The remainder of this page explains what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you a second time.
Petrol in a diesel: what does it do to your engine?
Passing through a motor, diesel is doing two jobs at once. Lubricating comes before burning; it does both. What stops the surfaces inside the high-pressure fuel pump and your injectors from wearing against one another is your diesel flowing through them — they're made to very fine clearances.
Poorly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, leaving a pump running on the blend wearing itself. It's also made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the rattling.
The shape of the problem is plain when you put those together. Contact doesn't do the harm — circulation does. Petrol in the tank is a fuel issue. Whatever a worn pump sheds goes on, carried by your fuel, into the injectors further along, which is why a pump that has been working on the petrol is where a mechanical problem begins.
Kilsby, petrol in a diesel: four situations, from mild to major
The best case there can be: filled up, never started. On a forecourt, and genuinely only there, that petrol is still confined to that tank — since everywhere else the car was driven to reach it. The job is emptying and cleaning on the spot.
Ignition on, or started for a second. The fuel system has been primed, so petrol has left the tank and got to the filter and the lines. Drain, flush, see to the fuel filter: still usually easy.
Your pump has spent a few miles on weakened fuel — that's what driving the car does. Miles is only half of that; how hard it was driven counts just as much. Either way this work includes your tank, your lines, the fuel filter and fresh fuel through the entire circuit. Short trips, such as the school run to Kilsby Church of England Primary School, are one thing. Driving as far as Coventry, under 15 miles away, makes a very different job — as does any miles on the M45, under a mile from Kilsby, with your engine working hard all the way.
Clattering, an uneven idle, smoke, a throttle gone soft: driven until it complained. The engine is telling you your fuel is no longer behaving like diesel. Stop on the spot — on the verge on Independent Street, at the kerb, down a side road — and do not move it again. A car pulled over quickly very rarely has permanent damage, since the drain and the flush-through, which still come first, take care of it.
Kilsby motorists and the petrol in a diesel myths they hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Topping up takes out nothing; it gives you a bigger tank of the same mix. Percentage isn't how a diesel fuel system tolerates petrol, however much that guidance presumes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through finer components: that's how a current diesel moves its fuel, and so the protection matters for more, not less.
"It starts, it drives, so there is no harm" — the myth that catches most motorists than any other. Diesel in a petrol motor normally leaves a motor that will not run: the driver stops, and so does the damage. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile your pump grinds. A running engine does not mean fine.
An outdated fix for a separate issue lies behind this one. Myth: "Add some two-stroke oil and drive it home." It does not put back what petrol has thinned, and the petrol is still in that tank later on.
The next start sends petrol back round your pump from your lines and the fuel filter, where some of that ends up once the engine has run. That is why draining your tank yourself doesn't sort it — a myth. Emptying petrol into a can by the roadside is also really hazardous.
How petrol ends up: petrol in a diesel
A careless moment is seldom the cause, and no one means to do it. One way only, since of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one mostly will not fit a petrol motor. That's how the forecourt makes it easy.
It happens when routine and the vehicle stop matching. Courtesy car, hire car, or a car that is new. A household with one petrol and one diesel on the driveway. A well-known forecourt with the pumps in a different order. Racing for a train at Rugby and filling up en route. Exactly the moment it occurs: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. With rain, a call arriving, or children to deal with, your hand just does what it has always done.
Kilsby motorists: how to prevent petrol in a diesel next time
- Check the petrol pump, not the colour. In the UK unleaded handles are generally green and diesel black, but not on each forecourt. The label is what matters.
- In a vehicle you don't know, look inside the flap over your filler or at the cap before the first fill: plenty of motors print the fuel there.
- One of each in the house? Label your key to your diesel — a coloured fob, a sticker — since meaning to remember isn't enough.
- Before the nozzle comes off the petrol pump the first time you fill a hired or new car, say "diesel" out loud. Daft, perhaps, yet it does the trick.
- Mistakes like this are simple to make while your mind is on something else, so the phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to block a petrol nozzle, and add-on devices exist for the remainder. Count it as a safety net, and keep reading the pump.
- The moment you realise, stop: less petrol in the tank means a thinner mix. What to do next does not change, though — still do not start the vehicle.
Put petrol in a diesel around Kilsby already?
Then, there is just a short order of things. Don't switch the ignition on, and do not crank it. Ask the staff to help you roll it away from the petrol pump if you're still at the forecourt, whether that's EG On the Move or somewhere else. Then phone 0333 366 0103 and tell us what got in, roughly how much, and whether it has run.
Say so if it was AdBlue rather than petrol: it's a separate fault, with its own page for Kilsby, since AdBlue brings corrosion and deposits instead of lost protection.
One petrol in a diesel job in Kilsby costs more than another. Why?
The four scenarios above are four different tasks, so no single quote for this would be honest. Mostly, your cost shifts with which one you're in. Beyond that it is the share — how much petrol was put in against how much your tank takes — and then where the car is and whether a technician can get to it safely.
Ahead of any quote, not after, we ask three questions: your fuel that went in, the volume, and whether it's run. That is why. The replies change a range into a straight figure.
About Kilsby, for a moment
Kilsby is a small village in Northamptonshire, situated on the banks of the River Avon at an elevation of 131 metres. Kilsby lies near the border with Warwickshire, close to the villages of Emery Row, Barby Nortoft, and Barby. Kilsby has a population of around 612 people, predominantly living in detached houses. Kilsby is located 14.8 miles from Coventry and 72.6 miles from London.
Fuel drain cover across Northamptonshire, Kilsby included
Emery Row, Barby Nortoft and Barby are among the places near Kilsby that the same teams work, answering petrol in diesel calls across Kilsby's CV postcode area. No need to move your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all places where we work.
Kilsby: still at the petrol pump?
In that case, you could not be in a better place. Switched off it stays; then call.