Harold Wood: Petrol in a Diesel Car? How Worried to Be
Far less than you probably are, if it has not been started. Everyone in Harold Wood starts with "have I ruined it?", and the honest answer is normally no: petrol resting in your tank of a diesel remains harmless until priming, cranking or driving pulls it into your fuel system. Leave the engine off and call Petrol in Diesel — that keeps it that way. What petrol actually does to a diesel, how to gauge how far it's travelled, and how to stop it from happening again: that's the remainder of this page.
The motor and petrol in a diesel: what happens
On its way through a motor, diesel has two tasks. Before it burns, it lubricates — and then it ignites. What stops the surfaces inside your high-pressure pump and your injectors from wearing against each other is your diesel flowing through them — they're built to very fine gaps.
Of these two tasks, petrol manages the first poorly and the second not at all. A pump working on a petrol mix is wearing itself out, since petrol is thinner than diesel and strips out the lubrication your fuel system depends 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 starts.
The shape of the issue is plain once you put those together. It is circulation that causes the harm, not contact. Where the petrol is only inside your tank, it is a fault of fuel, nothing more. The beginning of a mechanical one is a pump that has been running on that petrol — and whatever a worn pump sheds moves on with the fuel to the fuel injectors downstream.
Harold Wood, petrol in a diesel: four cases, from mild to significant
Fuelled but never started — as good as it gets. Only that tank has petrol in it, so the task is clearing the tank and purging the system where your car stands. This situation can only really happen on a forecourt: anywhere else, your car got there by being driven.
The ignition switched on, or a brief start. With your system primed, the fuel lines and filter now contain petrol that has come from the tank. Still normally easy: drain, flush, and your filter sorted.
Those few miles on the road meant the pump running on fuel diluted by petrol the whole way. Tank, lines, filter, then clean fuel run through the entire circuit: that is this work, and the way your car was driven counts as much as the miles. Short trips, like the school run to Harold Wood Primary School, are one matter. Very different a second time: a run to Chelmsford, under 15 miles away, or some distance on the M25, under 3 miles from Harold Wood, where your engine never stopped labouring hard.
Clattering, an uneven idle, smoke, a throttle gone soft: driven till it complained. The fuel is not acting like diesel any more, and your motor is telling you. Stop on the spot — on the verge on Saxon Close, at the kerb, down a side road — and don't move it. The fuel drain and flush-through still come first, and they deal with it: if a vehicle is pulled over quickly, lasting damage is very uncommon.
Stories Harold Wood drivers hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing is removed by topping up — you're left with a bigger tank, still the same mix. The assumption behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. A current diesel runs its fuel through smaller components at higher pressure, which makes the protection matter more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that catches motorists. Feed diesel to a petrol engine and it generally will not run, and so the driver stops — and the damage stops with them. While the pump wears, a diesel fed petrol usually starts, idles and drives away as though nothing has happened. A running engine doesn't mean fine.
Myth: a two-stroke additive lets you to drive home. It is an old fix, meant for another issue. What petrol has diluted stays diluted, and that petrol remains inside the tank anyway.
Myth: "Drain that tank yourself and you're sorted." Once the engine has run, some of the petrol is no longer in that tank: it's in the fuel filter and your lines, and it goes right back through your pump on the next start. Besides, petrol drained into a can by the road is genuinely dangerous.
How does petrol in a diesel happen?
Carelessness is seldom the cause, and nobody means to do it. The forecourt makes it easy: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle mostly will not go into a petrol car at all. So the mistake runs one way.
When habit and the vehicle stop matching, it takes place. Courtesy car, hire car, or a car that is brand new. Two cars on one drive, one petrol, one diesel. The pumps in a different order on a familiar forecourt. A rushed fill on the way to the nearest station with a train to catch. Years of petrol motors behind you, a diesel Renault Megane in front of you at the forecourt for its first tank — that is when. Your hand repeats what it has always done once you add rain, a phone call or a back seat full of children.
Avoiding petrol in a diesel next time you fill up in Harold Wood
- Read the pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on each forecourt. The label is what matters.
- The first fill in a strange motor is the time to check your filler flap — inside it, or on the cap, plenty of vehicles state which fuel they take.
- Label the 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 the 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, and so put your phone away and keep your mind on the petrol pump.
- Add-on devices exist for vehicles without one, and some diesels come with a filler that won't accept a petrol nozzle. Useful — but a safety net only, never a reason to stop checking the label.
- Less petrol means a weaker blend, so stop as soon as you realise — while remembering that the next stage is unchanged. It's still not to crank it.
Harold Wood: already put petrol in a diesel?
The order of things is brief, then. Don't fire it up, and don't turn the ignition on. If you're still at the forecourt — Tesco or anywhere else — ask the attendants to help you roll it away from the petrol pump. Next, 0333 366 0103. We will ask what went in, about how much, and if it has been run.
If it was AdBlue and not petrol, say so. That's a different fault — corrosion and deposits instead of lost lubrication — and it has its own page for Harold Wood.
Why one petrol in a diesel task around Harold Wood costs more than another
A fair single quote does not exist here: four situations, four separate jobs. Chiefly, the cost shifts with which one you're in. Two things follow that: the petrol that went in as a share of what your tank holds, then the spot your car is in and whether a van can get to it safely.
That is why our technicians ask three queries before costing instead of after: what went in, how much, and if it has run. With the replies, there is a straight figure instead of a range.
About Harold Wood and its setting
Harold Wood is a suburban area in Greater London, situated near the River Ingrebourne and characterised by semi-detached housing. Harold Wood sits at an elevation of 37 metres, approximately 16.5 miles from central London, and is close to nearby places such as Gallows Corner and Ardleigh Green. Harold Wood has a population of around 7960 residents and is located near Harold Park. Harold Wood is also relatively close to the city of Chelmsford, which is 14.4 miles away.
Harold Wood and Greater London: where our fuel drain cover runs
Petrol in diesel jobs in Harold Wood — part of the RM postcode area — go to teams that likewise cover the spots about it, Gallows Corner, Ardleigh Green and Harold Park included. Our technicians drain where your car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Still at the pump around Harold Wood?
The best place there is, then — that is where you are. Switched off it remains; then call.