Should You Worry? Petrol in a Diesel Car in Pitstone
Likely less than you already are — as long as nobody has started the vehicle. "Have I wrecked it?" is the first question everyone in Pitstone asks, and the truthful answer is normally no, since petrol left in a diesel tank harms nothing till it's drawn through the system — by ignition priming, by the starter, or by driving. Leave the motor off then call Petrol in Diesel — that keeps it that way. What petrol actually does to a diesel, how to judge how far it has gone, and how to stop it from happening again: that's the remainder of this page.
Petrol in a diesel: what does it do to the engine?
Diesel does two tasks on its way through an engine. It ignites, and before it ignites it protects. Designed to very fine clearances, your injectors and the pump rely on the diesel flowing through them to stop their surfaces wearing against one another.
Petrol handles the first job badly and the second not at all. A pump running on a petrol blend is wearing itself out, because petrol is thinner than diesel and takes away the lubrication your fuel system relies on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that is where the knocking comes.
Together, those leave the shape of the trouble clear. Not contact but circulation is what does the damage. Where that petrol is only inside your tank, it's an issue of fuel, nothing more. The start of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with your fuel to the fuel injectors downstream.
How serious is petrol in a diesel? Four scenarios we see around Pitstone
Fuelled up, not once started. The best case there can be. Only that tank has petrol in it, and so the job is draining your tank and rinsing your system where the vehicle stands. This scenario can only really occur at a forecourt: anywhere else, the car got there by being driven.
A brief spell of running, or merely the ignition on. Petrol has left the tank and got to the fuel filter and your lines, because your system has been primed. That is usually still a straightforward job — a drain, a flush, and the filter seen to.
The pump has worked a couple of miles on diluted fuel — that's what driving the car meant. How hard the car was driven matters as much as how far, and the work covers that tank, the fuel lines, the fuel filter and clean fuel through the whole circuit. The school run to Brookmead School is one matter. Driving as far as St Albans, under 15 miles away, makes a very different job — as does any mileage on the M1, under 10 miles from Pitstone, with the motor running hard all the way.
Driven until it protested. Clattering, a lumpy idle, smoke, a throttle that has gone soft. That is the motor telling you its fuel no longer is acting like diesel. Leave it wherever it has stopped: a lay-by, a side street, the verge on Marsworth Road. Long-term damage is very rare if a car is pulled over early, and the fuel drain and flush-through that still come first take care of it.
Pitstone people and that petrol in a diesel myths they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing is removed by topping up — you are left with a fuller tank, still the same mixture. Percentage isn't how a diesel fuel system copes with petrol, whatever that guidance assumes.
"Newer diesels can handle a little petrol" — a myth, and nearer the reverse. At higher pressure, through finer components: that's how a current diesel moves its fuel, and so the lubrication matters for more, not less.
"It starts, it drives, so no harm done" — the myth that trips up most drivers than any other. Any petrol engine fed diesel usually won't run, and so the motorist 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 grinds. Fine and running aren't the same thing.
An old workaround for a distinct fault is behind this one. Myth: "Add some two-stroke oil and drive the car home." It does not put back what petrol has weakened, and the petrol is still in your tank later on.
"Drain it yourself and you're sorted" — a myth, since after it has been running some petrol sits in your filter and lines, ready to go right back through your pump at the next start. It's also truly hazardous to drain petrol into a can at the roadside.
How petrol ends up: petrol in a diesel
It's seldom carelessness, and no one does it on purpose. The petrol nozzle is the slimmer of the two and slips into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol vehicle at all. The forecourt makes it simple, and the slip runs one way.
Habit and the vehicle getting out of step is how it occurs. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the drive. A familiar forecourt with the pumps in a different order. A train to catch, and a rushed fill en route to Cheddington. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it happens. With rain, a call coming in, or children to deal with, your hand just does what it has always done.
Next time you fill up in Pitstone: avoiding petrol in a diesel
- The label is what matters, and so read the pump rather than the colour: in the UK unleaded handles are usually green and diesel black, yet not on every forecourt.
- Many cars state the fuel type inside your filler flap or on the cap, and so check it on the first fill in a vehicle you don't know.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of intending to remember, for a home with one of each.
- It sounds daft and it works: on the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump.
- Put the phone away. This is an easy mistake to make while you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to reject a petrol nozzle, and add-on devices are available for cars without one. They are a safety net, not a reason to stop checking the pump.
- Less petrol makes a thinner mixture, so stop the moment you notice — though remembering that your next step is unchanged. It is still not to crank it.
Pitstone: already put petrol in a diesel?
The order of things is brief, then. Leave it unstarted, with the ignition switched off as well. Still at the forecourt, at Shell or anywhere else? Ask the attendants to help you push the vehicle away from the pump. Ring 0333 366 0103 next, with three facts — the fuel, the rough volume, and if it has run.
If it was AdBlue instead of petrol, say so. That is a separate issue — corrosion and deposits rather than lost protection — and it has its own page for Pitstone.
Why one petrol in a diesel task around Pitstone costs more than another
There is no fair single price for this, since the four situations above are four separate jobs. Mostly, the cost moves with which one you are in. Where the car is matters too, and whether a technician can safely get to it, after the share of petrol to what your tank takes.
Three queries come first, before quoting, instead of after — what went in, how much, has it run — and this is the reason. With the answers, there is a straight figure instead of a range.
About Pitstone, briefly
Pitstone is a village in Buckinghamshire, situated on the banks of the River Icknield Way, at an elevation of around 111 metres. Pitstone lies near the Chiltern Hills, with nearby settlements including Pitstone Green, Church End, and Ivinghoe. Pitstone has a population of approximately 1939 residents, predominantly living in detached housing. Pitstone is located 31.5 miles from London and 14.1 miles from St Albans, making it a rural village with access to larger urban areas.
Fuel drain cover in Pitstone and across Buckinghamshire
Petrol in diesel jobs around Pitstone — part of the LU postcode area — go to teams that likewise cover the locations round it, Pitstone Green, Church End and Ivinghoe included. You need not move your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all locations where we work.
Pitstone: still at the petrol pump?
Then you are in the best spot there is. Turned off it remains; then ring.