Should You Worry? Petrol in a Diesel Car in Newton
Likely less than you already are — as long as no one has started the car. Petrol sitting in a diesel tank does nothing to the engine till something draws it through your fuel system — your ignition priming your pump, the starter, or driving itself. So the truthful answer to the first query everyone in Newton asks, "have I wrecked it?", is normally no. Petrol in Diesel is who to phone, with the motor left off, so it remains that way. Below, this page sets out what petrol actually does inside a diesel, how far it may have got, and how to stop it happening to you again.
Petrol in a diesel: what does it do to the engine?
On its way through an engine, diesel has two jobs. Before it ignites, it protects — then it combusts. Your high-pressure pump and the fuel injectors are made to very fine clearances, and the diesel passing through them is what stops those surfaces from grinding against each other.
Of those two tasks, petrol handles the first badly and the second not at all. A pump running on a petrol mixture is wearing itself out, since petrol is runnier than diesel and strips out the lubrication the fuel system depends on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that is where any clattering comes.
The shape of the issue is clear when you put those together. The damage is done by movement, not by contact. Petrol in the tank is a fuel issue. Whatever a worn pump sheds goes on, carried by the fuel, into your injectors downstream, which is why a pump that has worked on that petrol is where a mechanical problem starts.
How bad is petrol in a diesel? Four scenarios our technicians see in Newton
The best case there is: filled up, never started. Just that tank has petrol in it, so the job is emptying your tank and rinsing the fuel system where the car stands. This situation can only truly take place on a forecourt: anywhere else, the vehicle got there by being driven.
A moment's running, or merely your ignition on. With your system primed, your lines and filter already hold petrol that has come from that tank. Drain, flush, deal with your filter: still usually simple.
Your pump has worked a few miles on diluted fuel — that's what driving the car meant. How hard your car was driven matters as much as how far, and the work takes in the tank, the lines, your filter and fresh fuel through the whole circuit. A school run to Newton Bluecoat Church of England Primary School is one thing. Getting as far as Preston, under 10 miles away, makes a very different job — as does any mileage on the M55, under 3 miles from Newton, with the engine labouring hard all the way.
It complained, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone lumpy. That's your engine telling you its fuel has stopped behaving like diesel. Pull up on the spot — on the verge on Grange Lane, at the kerb, down a side road — and do not move it. A car stopped early very rarely has lasting damage, as the fuel drain and the flush-through, which still go first, take care of it.
What Newton motorists get told about petrol in a diesel — and the myths in it
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. Nothing is removed by topping up — you're left with a fuller tank, still the same mixture. A diesel fuel system doesn't tolerate petrol by percentage in the way that guidance presumes.
Not so: a modern diesel copes with a bit of petrol. If anything, the reverse. Lubrication counts more on modern diesels, not less, since their fuel runs through smaller components at higher pressure.
This is the one that catches motorists. Myth: "If it starts and drives, there's no harm done." Feed diesel to a petrol motor and it generally will not run, so the driver stops — and the harm stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump wears. Fine and running aren't the same at all.
Myth: "Add some two-stroke oil and drive it home." It is an old fix for a separate fault. What petrol has weakened stays thinned, and the petrol stays in that tank anyway.
If the engine has been run, part of that petrol is in your filter and the lines, not your tank — and the next start pulls it right back through your pump. So the myth "drain your tank yourself and you are sorted" doesn't stand up. Clearing petrol into a can by the roadside is also genuinely dangerous.
Petrol in a diesel: how does it occur?
A careless moment is rarely the cause, and nobody means to do it. A diesel nozzle generally won't fit a petrol vehicle, yet the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error easy, and only in one direction.
It occurs when routine and your car stop matching. Hire cars, courtesy cars, and vehicles that are new to you. Two cars on one drive, one petrol, one diesel. Your usual forecourt, its pumps now in a different order. A hurried fill en route to Salwick with a train to catch. Years of petrol vehicles behind you, a diesel Volkswagen Golf in front of you at the forecourt for its first tank — that's when. Throw in a back seat full of kids, a phone call or rain, and habit takes over.
How to prevent petrol in a diesel on your next fill-up around Newton
- A green handle for unleaded and black for diesel is usual in the UK — but not on each forecourt. Go by the label on the petrol pump, not the colour.
- In a car you don't know, look inside the flap over your filler or at the cap before your first fill: plenty of motors state the fuel type there.
- One of each in the house? Mark the key to your diesel — a bright fob, a sticker — because intending to remember isn't enough.
- "Diesel", out loud, before you lift the nozzle — each time a new or hired car gets its first tank. It sounds daft. It does the trick.
- Mistakes like this are easy to make while your mind is on something else, so the phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to refuse a petrol nozzle, and add-on devices are available for the remainder. Treat it as a safety net, and keep reading the pump.
- As soon as you realise, stop: less petrol in that tank means a weaker mix. What to do next doesn't change, though — still don't start the car.
Already put petrol in a diesel in Newton?
Then the order of things is brief. Do not crank it, and do not turn the ignition on. Yet at the forecourt, at Texaco or anywhere else? Ask the attendants to help you push the vehicle clear of the pump. Then ring 0333 366 0103 and tell us what got in, about how much, and if it has run.
If it was AdBlue rather than petrol, say so. That is a separate problem — corrosion and deposits rather than lost lubrication — and it has its own page for Newton.
Why one petrol in a diesel job in Newton costs more than another
The four situations above are four separate jobs, so no single price for this would be fair. Mostly, the cost moves with which one you're in. Where the vehicle is counts too, and whether a van can safely get to it, after the proportion of petrol to what that tank holds.
What got in, how much, and whether it has run — three queries our technicians ask before costing, not after, for exactly that reason. The answers change a range into a straight figure.
About Newton itself
Newton is a suburban area in Lancashire, situated inland at an elevation of 18 metres, approximately 5.8 miles from Preston. Newton forms part of the wider Preston urban area, with nearby places including Newton-with-Scales, Dowbridge, and Clifton. Newton has a population of around 845 people, predominantly living in detached housing.
Fuel drain cover across Lancashire, Newton included
Petrol in diesel calls in Newton — part of the PR postcode area — go to teams that also cover the spots around it, Newton-with-Scales, Dowbridge and Clifton among them. You need not bring the car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all locations where we work.
In Newton and still at the pump?
The best spot there is, then — that is where you are. Leave the vehicle turned off, then ring.