How Worried Should You Be? Petrol in a Diesel Car in Great Bookham
Probably less than you are now — as long as no one has started the car. Petrol sitting in a diesel tank does nothing to your motor till something pulls it through the system — your ignition priming your pump, the starter, or the drive itself. So the fair answer to the first query anyone in Great Bookham asks, "have I ruined it?", is generally no. To leave the vehicle that way, ring Petrol in Diesel and leave the engine alone. The remainder of this page explains what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you a second time.
Your engine and petrol in a diesel: what happens
On its way through a motor, diesel does two tasks. Before it burns, it protects — and then it combusts. Extremely fine tolerances go into the fuel injectors and the high-pressure fuel pump, and just your diesel running through keeps those surfaces from grinding together.
Badly at the first, not at all at the second: that's petrol. A pump working on a petrol mix is wearing itself out, because petrol is runnier than diesel and strips out the lubrication the fuel system relies on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that's where any knocking comes.
The shape of the trouble is plain when you put those together. Not contact but circulation is what causes the damage. Petrol in the tank is a fuel issue. Whatever a worn pump sheds goes on, borne by your fuel, into the fuel injectors downstream, which is why a pump that has been working on the petrol is where a mechanical issue starts.
Four scenarios we see in Great Bookham: how bad is petrol in a diesel?
Filled but never started — the best it gets. Just that tank has petrol in it, and so the task is emptying the tank and purging the system where the car stands. This situation can only truly take place on a forecourt: anywhere else, your car got there by being driven.
Started for a moment, or only your ignition on. Once primed, the system has drawn petrol from your tank up to the filter and the lines. That is normally still an easy task — a drain, a flush, and the fuel filter dealt with.
Your pump now spent a few miles on weakened fuel — that's what driving the car meant. Miles is only half of that; how hard it was driven counts just as much. Either way this work includes your tank, the fuel lines, the fuel filter and fresh fuel through the whole circuit. A school run to Great Bookham School is one thing. Any distance on the M25, under 3 miles from Great Bookham, means the engine has worked hard throughout, and a run to Westminster, under 25 miles away, is a very different task too.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone uneven. The engine is telling you your fuel is no longer acting like diesel. Leave it where it has stopped: a lay-by, a quiet street, the verge on Church Road. Permanent damage is very rare when a vehicle is pulled over quickly, and the drain and flush that still go first take care of it.
What Great Bookham motorists get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." A fuller tank of the same mixture is all it gives, since topping up removes nothing. Percentage is not how a diesel fuel system tolerates petrol, whatever that guidance assumes.
"Newer diesels can handle a little petrol" — a myth, and closer to the reverse. At higher pressure, through finer parts: that's how a modern diesel moves its fuel, and so the protection matters more, not less.
One myth that catches drivers out: if it starts and drives, it must be unharmed. The driver of a petrol engine fed diesel normally stops, because it will not run, and the damage stops there. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile your pump wears. Fine and running are not the same thing.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a distinct issue. That petrol is still inside that tank after that, and what it has weakened is not put back.
If your engine has been run, part of the petrol is in the fuel filter and the lines, not your tank — and the next start pulls it right back through the pump. So the myth "drain that tank yourself and you are sorted" doesn't hold. And, a can of petrol filled at the kerbside is truly hazardous.
How does petrol in a diesel take place?
No one does it on purpose, and it is rarely carelessness. A diesel nozzle generally won't fit a petrol car, yet the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake simple, and just in one direction.
It takes place when habit and the car stop matching. A new motor, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. A familiar forecourt with the pumps in a different order. Racing for a train outside Bookham and fuelling up en route. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist used to petrol: precisely when it happens. Add rain, a phone call or a back seat full of children, and your hand does what it has always done.
Next time you fill up around Great Bookham: avoiding petrol in a diesel
- The label is what counts, and so check the pump instead of the colour: in the UK unleaded handles are usually green and diesel black, but not on each forecourt.
- In a vehicle you do not know, look inside the flap over your filler or at the cap before your first fill: many motors state the fuel there.
- Label the key. In a home with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember.
- "Diesel", aloud, before you pick up the nozzle — each time a new or hired car needs its first tank. It seems silly. It works.
- While you're thinking about something else, this is an easy mistake to make — so put the phone away.
- Add-on devices are available for cars without one, and some diesels come with a filler that will not accept a petrol nozzle. Helpful — but a backstop only, never a reason to stop checking the label.
- Less petrol means a thinner mix, and so stop as soon as you notice — though remembering that your next stage is unchanged. It is still not to fire it up.
Already put petrol in a diesel in Great Bookham?
Then, there is only a short order of things. Never crank it, and do not turn the ignition on. If you're still on the forecourt — Esso or anywhere else — ask the staff to help you roll the car clear of the pump. Then call 0333 366 0103 and tell us what went in, roughly how much, and whether it's run.
Corrosion and deposits form the trouble with AdBlue, where petrol means lost lubrication. So if it was AdBlue, say so — and read its own Great Bookham page.
One petrol in a diesel task around Great Bookham costs more than another. Why?
There is no fair single price for this, since the four scenarios above are four different tasks. Chiefly, the cost shifts with which one you're in. The ratio matters next, meaning how much of the tank is petrol, followed by the position of the car and whether reaching it is safe for our van.
Ahead of any quote, not after, we ask three questions: the fuel that went in, its quantity, and if it's run. That is why. Their answers are what change a range into one firm number.
About Great Bookham, briefly
Great Bookham is a locality in Surrey, situated inland at an elevation of 68 metres, approximately 19 miles from London. Great Bookham has a population of around 2153 people and is characterised by predominantly detached housing. Great Bookham is located near other settlements such as Little Bookham and Fetcham, and is also within reach of the coast, although the Isle of Wight is a significant distance away. Great Bookham sits within the South East region of England, with Westminster being the nearest major city.
Fuel drain cover across Surrey, Great Bookham included
Petrol in diesel call-outs around Great Bookham — part of the KT postcode area — go to teams that likewise cover the spots around it, Little Bookham, Fetcham and Isle of Wight included. A forecourt, a supermarket car park, a lay-by or your own drive are all spots our technicians work, and the car doesn't need to move to us.
Still at the petrol pump around Great Bookham?
Nothing beats it: that is where you now are. Switched off it stays; then ring.