Longlevens: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — as long as nobody has started it. Till your ignition primes your pump, your starter turns, or the car is driven, petrol in a diesel tank simply waits there and does nothing. Which means the truthful reply to the first Longlevens question — "have I ruined it?" — usually no. To leave the vehicle like that, phone Petrol in Diesel and leave the engine switched off. Further down, you will find what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
Inside the motor: what petrol in a diesel really does
Passing through a motor, diesel does two jobs at the same time. Oiling comes before burning; it does both. What keeps the surfaces inside the high-pressure pump and your injectors from wearing against one another is your diesel passing through them — they are made to extremely fine gaps.
Of those two jobs, petrol manages the first poorly and the second not at all. A pump working on a petrol blend is wearing itself out, since petrol is thinner than diesel and strips out the protection the fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that's where the knocking comes.
Seen together, they show what shape the issue takes. Not contact but circulation is what causes the damage. Any tank with petrol in it is a fuel problem. A pump that has been working on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with your fuel to your injectors further on.
Longlevens, petrol in a diesel: four cases, from mild to serious
Filled up, never started. The best case there can be. Only your tank has petrol in it, and so the job is clearing that tank and rinsing your system where the vehicle sits. This situation can only really happen at a forecourt: anywhere else, the car got there by being driven.
Ignition on, or started for a second. With the system primed, your lines and filter now hold petrol that has come from the tank. That is normally still a simple job — a drain, a flush, and the filter seen to.
Those few miles driven meant your pump labouring on fuel thinned by petrol the whole way. Mileage is only half of it; how hard it was driven counts just as much. Either way this work includes the tank, the fuel lines, your filter and fresh fuel through the whole circuit. Short trips, such as the school run to Longlevens Junior School, are one matter. Any miles on the M5, under 3 miles from Longlevens, means the engine working hard throughout, and a run to Gloucester, under 3 miles away, is a very different job too.
Driven until it protested. Knocking, a ragged idle, smoke, a throttle that has gone soft. That's the engine telling you its fuel no longer is acting like diesel. Pull up on the spot — on the verge on Church Road, at the kerb, down a side road — and do not move it. The drain and flush still go first, and they deal with it: when a car is stopped soon, permanent damage is very uncommon.
What Longlevens motorists get told about petrol in a diesel — and the myths in it
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing comes out when you top up — that tank just holds more of the same blend. Percentage is not how a diesel fuel system copes with petrol, whatever that advice presumes.
Not so: a newer diesel copes with a bit of petrol. If anything, the reverse. Protection matters more on newer diesels, not less, since their fuel passes through more precise components at higher pressure.
Myth: "If it starts and drives, there is no harm done." This is the one that catches motorists. Feed diesel to a petrol engine and it usually won't run, and so the driver stops — and the harm stops with them. Whilst the pump wears, a diesel fed petrol normally starts, ticks over and drives away as if nothing has happened. Running doesn't mean fine.
Not so: a two-stroke additive makes it safe to drive home. It was an old workaround, supposed for another fault. What petrol has diluted stays weakened, and the petrol stays in your tank regardless.
Myth: "Drain the tank yourself and you are sorted." After the engine has been run, some of that petrol is no longer in your tank: it is in the filter and the lines, and it goes straight back through the pump at your next start. Also, a can of petrol filled by the kerbside is truly hazardous.
Why petrol in a diesel happens at all
Carelessness is seldom the cause, and nobody means to do it. 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 mistake runs one way.
When routine and your car stop matching, it takes place. A new vehicle, a hire car or a courtesy car. Households running one of each, petrol and diesel. The pumps in a different order on a familiar forecourt. A rushed fill en route to Gloucester with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a motorist accustomed to petrol: precisely when it happens. The hand does what it has always done when you add rain, a phone call or a back seat full of kids.
How to avoid petrol in a diesel on your next fill-up around Longlevens
- The label is what matters, so read the pump rather than the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- Check your filler flap. Plenty of vehicles state the fuel inside the flap or on the cap. Look at it on the first fill in a car you do not know.
- Label your key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol 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 have a filler designed to refuse a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the petrol pump.
- The moment you realise, stop: less petrol inside the tank means a thinner mixture. What to do next does not change, though — still do not crank it.
Put petrol in a diesel in Longlevens already?
Then, there is only a short order of things. Do not turn the ignition on, and don't fire it up. Ask the staff to help you roll it away from the petrol pump if you're still at the forecourt, whether that is Esso or anywhere else. What got in, roughly how much, and if it's run: tell us that when you ring 0333 366 0103.
If it was AdBlue rather than petrol, say so. That's a different issue — corrosion and deposits rather than lost protection — and it has its own page for Longlevens.
Why one petrol in a diesel job in Longlevens costs more than another
Four separate jobs sit behind the four scenarios above — which is why there is no honest single quote. The scenario itself does most of the work of moving your cost. The share counts next, meaning how much of the tank is petrol, and then the location of the vehicle and whether reaching it is safe for a van.
What was put in, how much, and whether it's run — three queries our technicians ask before pricing, not after, for precisely that reason. Those replies are what turn a range into one firm number.
About Longlevens itself
Longlevens is a suburban area located on the outskirts of Gloucester, situated near the River Severn in Gloucestershire. Longlevens sits at an elevation of 19 metres, with its riverside setting influencing the local environment. Longlevens is characterized by its predominantly semi-detached housing stock, which reflects the area's residential development. Longlevens is close to nearby places such as Elmbridge, Wotton, and Longford, and is approximately 1.6 miles from Gloucester city centre.
Across Gloucestershire and around Longlevens: fuel drain cover
Petrol in diesel calls around Longlevens — part of the GL postcode area — go to vans that likewise cover the locations round it, Elmbridge, Wotton and Longford included. Our engineers drain where your vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
In Longlevens and still at the petrol pump?
The best position there is, then — that is where you are. Turned off it stays; then phone.