How Worried Should You Be? Petrol in a Diesel Car in Smeeth
Provided it hasn't been started, you can worry far less than you likely are. Everyone in Smeeth starts with "have I ruined it?", and the honest answer is generally no: petrol left inside your tank of a diesel stays harmless until priming, cranking or driving draws it into your fuel system. To keep it that way, ring Petrol in Diesel then leave your motor alone. The rest of this page covers 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 again.
Inside the motor: what petrol in a diesel does
Diesel does two jobs on its way through a motor. Before it burns, it lubricates — then it combusts. Designed to extremely fine tolerances, the injectors and the pump depend on the diesel flowing through them to keep their surfaces from wearing against one another.
Petrol handles the first task poorly and the second not at all. Being less viscous than diesel, petrol strips out the protection a fuel system needs, so a pump running on that mixture wearing itself. It's equally made to resist igniting under compression — the opposite of what a diesel needs — which is where you hear the knocking.
The shape of the trouble is clear once you put those together. It is circulation that causes the harm, not contact. Petrol in a tank is a fuel issue. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with your fuel to your injectors further on.
How serious is petrol in a diesel? Four situations our engineers see around Smeeth
Filled up, and not started: no case is better. At a forecourt, and really only there, the petrol is still limited to the tank — since anywhere else the vehicle 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 that tank and got to the fuel filter and the lines. Still usually simple: drain, flush, and your filter seen to.
Driven a couple of miles. Now the pump has spent those miles working on thinned fuel. How hard the vehicle was driven matters as much as how far, and this work covers the tank, the lines, the filter and clean fuel through the whole circuit. Short trips, like the school run to Smeeth Community Primary School, are one thing. Very different again: a run to Canterbury, under 15 miles away, or some mileage on the M20, under a mile from Smeeth, where the engine kept working hard.
Driven till it complained. Rattling, a lumpy idle, smoke, a throttle that has gone soft. What you are hearing is the engine reporting fuel that no longer behaves like diesel. Leave it where it stops: a lay-by, a quiet street, the verge on Church Road. A car stopped quickly very seldom has permanent damage, since the drain and the flush-through, which still go first, deal with it.
What Smeeth motorists get told about petrol in a diesel — and the stories in it
False: topping up to full with diesel makes it fine. It does not. Topping up removes nothing; it gives you a fuller tank of the same mixture. That guidance presumes a diesel fuel system tolerates petrol by percentage. It doesn't.
Not so: a modern diesel copes with a bit of petrol. If anything, the opposite. Protection matters more on modern diesels, not less, because their fuel passes through smaller parts at higher pressure.
One myth that catches motorists out: if it starts and drives, it must be unharmed. Diesel in a petrol motor generally leaves a motor that will not run: the motorist stops, and so does the damage. A diesel fed petrol generally starts, idles and drives away as though nothing has happened, whilst the pump wears. Running is not the same as fine.
Myth: "Add some two-stroke oil and drive the car home." It's an old workaround for a distinct fault. It does not put back what petrol has diluted, and the petrol is still inside your tank later on.
"Drain it yourself and you are sorted" — a myth, because after it has been running some petrol lies in the fuel filter and lines, ready to go straight back through the pump at the next start. Also, a can of petrol drained by the kerbside is truly hazardous.
Petrol in a diesel: how does it occur?
It is rarely carelessness, and no one does it on purpose. The petrol nozzle is the narrower of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol motor at all. The forecourt makes it simple, and the mistake runs one way.
It happens when habit and your car stop matching. A new vehicle, a hire car or a courtesy car. Two vehicles on one driveway, one petrol, one diesel. The pumps in a different order on a familiar forecourt. A hurried fill on the way to Westenhanger 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 is when. With rain, a call coming in, or a car full of children to deal with, your hand simply does what it has always done.
Next time you fill up in Smeeth: avoiding petrol in a diesel
- Read the pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on every forecourt. The label is what counts.
- Many vehicles state the fuel type inside the filler flap or on the cap, and so check there on your first fill in a vehicle you do not know.
- Good intentions count for less than a sticker or a fob in a bright colour on the diesel's key when a house has one of each. So label it.
- Before the nozzle comes off the pump the first time you fill a hired or new car, say "diesel" out loud. Silly, perhaps, but it does the trick.
- Mistakes like this are straightforward to make while your mind is on something else, so the phone goes away.
- Some diesels have a filler designed to reject a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the petrol pump.
- Less petrol makes a thinner mix, so stop the moment you notice — though remembering that your next stage is unchanged. It is still not to fire it up.
Petrol already in a diesel in Smeeth? Begin here
Then the order of things is short. Starting it is out, and so is turning on the ignition. The staff on the forecourt — whether at John Childs Garages itself or wherever you filled up — will usually help push it away from the pump if you ask. Then call 0333 366 0103 and tell us what got in, roughly how much, and whether it's run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a different issue — Smeeth has a page all for it.
What makes one Smeeth petrol in a diesel job cost more than the next
The four scenarios above are four different jobs, so no single price for this would be honest. The situation itself does most of the work of moving your cost. Beyond that it's the proportion — how much petrol got in against how much your tank holds — and after that where the car is and whether our van can get to it safely.
That is why our engineers ask three questions before pricing instead of after: what got in, how much, and if it's run. Their answers are what turn a range into one firm number.
About Smeeth, for a moment
Smeeth is a small village in Kent, situated inland at an elevation of 89 metres, approximately 11.9 miles from Canterbury. Smeeth lies within a rural area, surrounded by nearby places such as Ridgeway, Brabourne Lees, and Lilyvale. Smeeth has a population of around 520 people, predominantly living in semi-detached housing.
Fuel drain cover across Kent, Smeeth included
Ridgeway, Brabourne Lees and Lilyvale are among the places around Smeeth that the same teams work, answering petrol in diesel jobs across Smeeth's TN postcode area. You need not bring the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots where we work.
Still at the pump around Smeeth?
Then you're in the best spot there is. Call, and keep it turned off.