Higher Reen: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less worried than you probably feel. Petrol resting in a diesel tank does nothing to the motor till something pulls it through the system — the ignition priming the pump, your starter, or the drive itself. So the fair answer to the first question anyone around Higher Reen asks, "have I ruined it?", is normally no. Leave your engine off and ring Petrol in Diesel — that is how you keep it that way. What petrol actually does to a diesel, how to gauge how far it's gone, and how to keep it from happening again: that's the rest of this page.
Your engine and petrol in a diesel: what happens
Diesel does two jobs on its way through a motor. It burns, and before it ignites it protects. What stops the surfaces inside your high-pressure pump and your injectors from grinding against each other is your diesel passing through them — they're built to very fine tolerances.
Petrol handles the first task badly and the second not at all. The clattering comes from petrol being designed not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips away the lubrication your system hinges on, and any pump working on that mixture is wearing itself.
Put those together and the shape of the issue is clear. It is movement that does the damage, not contact. Any tank with petrol in it is a fuel issue. A pump that has been working on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with your fuel to your injectors downstream.
Petrol in a diesel in Higher Reen: how bad is it? Four situations
Filled but never started — as good as it gets. Only your tank has petrol in it, so the task is clearing that tank and purging the system where the car sits. This scenario can only really take place at a forecourt: anywhere else, the vehicle got there by being driven.
The ignition switched on, or a brief start. With the fuel system primed, the fuel lines and filter now hold petrol that came from your tank. Still generally straightforward: drain, flush, and the filter seen to.
Driven a few miles. Now your pump has spent those miles labouring on weakened fuel. How hard your car was driven counts as much as how far, and this work takes in the tank, the lines, the fuel filter and fresh fuel through the whole system. On the school run to Perranporth Community Primary School, the distance is small. Driving as far as Truro, under 10 miles away, makes a very different task — as does any miles on the M5, over 50 miles from Higher Reen, with the engine labouring hard the whole time.
Rattling, a ragged idle, smoke, a throttle gone soft: driven till it complained. The motor is telling you the fuel is no longer acting like diesel. Whether it is the verge on B3285, a lay-by or a side road, stop there then leave it. The drain and flush-through still come first, and they take care of it: if a car is stopped soon, permanent damage is very uncommon.
What Higher Reen motorists get told about petrol in a diesel — and the myths in it
False: topping up to full with diesel makes it fine. It does not. A fuller tank of the same mix is all it gives, because topping up takes out nothing. A diesel fuel system doesn't accept petrol by percentage in the way that guidance assumes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. A newer diesel sends its fuel through more precise components at higher pressure, which makes the lubrication matter more, not less.
"It starts, it drives, so no harm done" — the myth that catches most people than any other. Any petrol engine fed diesel generally won't run, so the motorist stops and the harm stops with them. Feed petrol to a diesel and it normally starts, idles and drives away like nothing happened — all the while its pump wears. A running engine doesn't mean fine.
Not so: a two-stroke additive lets you to drive home. It was an old fix, meant for another problem. What petrol has thinned remains weakened, and that petrol remains inside that tank regardless.
Once the engine has been run, part of the petrol sits in the filter and the lines, not the tank — and the next start pulls it right back through your pump. So the myth "drain that tank yourself and you're sorted" doesn't stand up. And, a can of petrol filled at the kerbside is truly dangerous.
Petrol in a diesel: how does it take place?
Nobody does it on purpose, and it's rarely carelessness. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol motor at all. The forecourt makes it easy, and the error runs one way.
The moment habit stops matching the car is the moment it takes place. A new motor, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. A forecourt you know, only with its pumps laid out differently. A hurried fill en route to Newquay with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver used to petrol: exactly when it occurs. With rain, a call coming in, or children to deal with, the hand just does what it has always done.
Preventing petrol in a diesel next time you fill up in Higher Reen
- The label is what counts, so check the pump rather than the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- The first fill in a strange vehicle is the time to check the filler flap — inside it, or on the cap, many motors state which fuel to use.
- Good intentions do less than a sticker or a fob in a bright colour on your diesel's key when a household has one of each. So mark it.
- Before the nozzle leaves the pump the first time you fuel a hired or new motor, say "diesel" aloud. Silly, yes, yet it does the trick.
- Mistakes like this are straightforward 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 aftermarket devices exist for the rest. Count it as a safety net, and keep checking the petrol pump.
- As soon as you notice, stop: less petrol inside that tank means a thinner blend. What to do next does not change, though — still don't start the car.
Higher Reen: already put petrol in a diesel?
The order of things is brief, then. Do not turn the ignition on, and do not fire it up. If you're still on the forecourt — Texaco or anywhere else — ask the staff to help you push it away from the pump. Next, 0333 366 0103. We will ask what went in, about how much, and if it's been run.
If it was AdBlue and not petrol, say so. That is a separate fault — corrosion and deposits instead of lost lubrication — and it has its own page for Higher Reen.
What makes one Higher Reen petrol in a diesel job cost more than the next
The four scenarios above are four different tasks, so no single quote for this would be fair. Which of them you're in is mostly what shifts your cost. The share matters next, meaning how much of the tank is petrol, followed by the location of the vehicle and whether getting to it is safe for our van.
Ahead of any quote, not after, we ask three questions: the fuel that was put in, the volume, and if it has run. That is why. With the answers, there is a straight figure rather than a range.
About Higher Reen, for a moment
Higher Reen is a small coastal hamlet in Cornwall, situated approximately 80 metres above sea level and 6.6 miles from Truro. Higher Reen is characterized by its detached housing and quiet residential atmosphere, with nearby places including Rose, Reen Manor, and Lower Rose. Higher Reen sits within a scenic coastal area, with the South West Coast Path nearby, and is home to around 511 residents.
Higher Reen and Cornwall: where our fuel drain cover runs
Higher Reen sits in the TR postcode area, and our vans that answer petrol in diesel calls there work the spots around it as well — Rose, Reen Manor and Lower Rose among them. The vehicle does not need to move to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
At the pump around Higher Reen, right now?
Then you're in the best position there can be. Phone, and keep it switched off.