Should You Worry? Petrol in a Diesel Car in Craigie
Unstarted? Then less anxious than you probably are. "Have I wrecked it?" is the first question everyone around Craigie asks, and the truthful answer is normally no, because petrol resting in a diesel tank hurts nothing till it's drawn through your fuel system — by ignition priming, by your starter, or by driving. To leave it like that, call Petrol in Diesel and leave the motor alone. The remainder of this page sets out what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you again.
Inside your engine: what petrol in a diesel does
Passing through a motor, diesel does two jobs at once. It lubricates to begin with, and after that does it burn. Very fine gaps go into the injectors and your high-pressure pump, and just your diesel running through stops their surfaces grinding together.
Badly at the first, not at all at the second: that is petrol. The rattling comes from petrol being made not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips out the protection your system hinges on, and any pump running on that blend is wearing itself.
Combined, those make the shape of the problem plain. It is circulation that causes the damage, not contact. All a tank with petrol in it amounts to is a fuel problem. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with your fuel to the fuel injectors downstream.
Craigie, petrol in a diesel: four cases, from mild to significant
Filled up, never started. The best case there is. The petrol is inside that tank and only the tank, and the task is a drain and a flush where the vehicle stands. This is the one scenario that can only really happen on a forecourt, as anywhere else the vehicle has been driven to get there.
The ignition switched on, or a short start. The system has been primed, and so petrol has left your tank and reached the filter and your lines. Still normally straightforward: drain, flush, and the fuel filter seen to.
Your pump has spent a couple of miles on weakened fuel — that's what driving it meant. Tank, lines, filter, then fresh fuel run through the whole system: that is the work, and the way your car was driven matters as much as the miles. Short trips, such as the school run to the local primary school, are one matter. Very different once more: a run to Perth, under a mile away, or some miles on the M90, under a mile from Craigie, where the engine kept running hard.
It complained, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone ragged. The fuel isn't acting like diesel any more, and the engine is saying so. Stop where you are — on the verge on Darnhall Drive, at the kerb, down a side road — and do not move it. What comes first is still the drain and flush, and that deals with it, with long-term damage very rare when a car is pulled over early.
Myths Craigie motorists hear about petrol in a diesel
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Topping up removes nothing; it gives you a fuller tank of the same mix. Percentage is not how a diesel fuel system copes with petrol, whatever that guidance assumes.
"Current diesels can handle a little petrol" — a myth, and closer to the opposite. Protection matters more on modern diesels, not less, because their fuel passes through smaller parts at higher pressure.
Myth: "If it starts and drives, there is no damage done." This is the one that fools people. Diesel in a petrol motor usually leaves a motor that won't run: the motorist stops, and so does the harm. Feed petrol to a diesel and it generally starts, ticks over and pulls away like nothing has happened — all the while its pump wears. A running engine does not mean fine.
Myth: a two-stroke additive lets you to drive home. It is an old fix, meant for another fault. What petrol has diluted remains weakened, and that petrol remains in that tank regardless.
Once your engine has been run, part of that petrol is in the fuel filter and the fuel lines, not your tank — and the next start pulls it straight back through your pump. So the myth "drain the tank yourself and you are sorted" doesn't hold. Besides, petrol drained into a can by the road is truly hazardous.
How does petrol in a diesel occur?
It is rarely carelessness, and nobody does it on purpose. The forecourt makes it simple: the petrol nozzle is the smaller of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle generally will not go into a petrol car at all. So the error runs one way.
The moment habit stops matching the car is the moment it occurs. A new vehicle, a hire car or a courtesy car. Two motors on one driveway, one petrol, one diesel. The pumps in a different order on a well-known forecourt. A train to catch, and a rushed fill en route to Perth. The first fill-up in a diesel Renault Megane after years of driving petrol is exactly the moment it happens. Throw in a back seat full of children, a phone call or rain, and the hand wins.
Craigie drivers: how to prevent petrol in a diesel next time
- 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 pump, not the colour.
- In a car 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.
- Mark the key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump. It sounds daft and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away and keep your mind on the pump.
- Some diesels come with a filler built to reject a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- Spotting it halfway? Stop there and then. A thinner blend results from less petrol in that tank, yet the next stage stays the same: don't crank it.
Craigie: already put petrol in a diesel?
Short and simple, then, is the order of things. Don't switch the ignition on, and do not crank it. Yet on the forecourt, at Morrisons or anywhere else? Ask the attendants to help you push the car away from the pump. Then phone 0333 366 0103 and tell us what got in, roughly how much, and if it's run.
Corrosion and deposits form the problem with AdBlue, whereas petrol brings lost protection. So if it was AdBlue, say so — and read its own Craigie page.
What makes one Craigie petrol in a diesel job cost more than the next
The four situations above are four different jobs, so no single price for this would be fair. What shifts your cost is mostly which of them you're in. Where the vehicle is matters too, and whether a technician can safely get to it, after the proportion of petrol to what your tank holds.
Ahead of any quote, not after, come three queries: your fuel that got in, the quantity, and if it's run. That's why. A range turns into a straight figure once the answers are in.
About Craigie itself
Craigie is a suburban area located on the riverside in Perth and Kinross, Scotland, with a relatively low elevation of 31 metres. Craigie sits close to the city of Perth, being only 0.5 miles away, and is near other nearby places such as Cherrybank and Woodlands. Craigie is predominantly composed of flat-type housing, which accommodates its population of approximately 4855 residents. Craigie is situated in a scenic area, with the River Tay flowing nearby.
Craigie and Perth and Kinross: where our fuel drain cover runs
Craigie waits in the PH postcode area, and the vans that answer petrol in diesel call-outs there work the places near it as well — Cherrybank, Perth and Woodlands among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all places our technicians drain, and your car does not need to come to us.
At the petrol pump around Craigie, still?
Nothing beats it: that's where you are. Phone, and keep it turned off.