How Worried Should You Be? Petrol in a Diesel Car in Lakenheath
Far less than you likely are, provided it hasn't been started. Till the ignition primes the pump, your starter cranks, or the car is driven, petrol in a diesel tank simply waits there and does nothing. Which makes the truthful reply to that first Lakenheath question — "have I wrecked it?" — usually no. Leave your engine off then call Petrol in Diesel — that is how you keep it like that. Further down, this page sets out what petrol actually does inside a diesel, how far it might have gone, and how to stop it happening to you again.
What petrol in a diesel does to the motor
On its way through an engine, diesel does two jobs. It burns, and before it ignites it lubricates. Made to very fine clearances, the injectors and your pump depend on your diesel moving through them to stop their surfaces wearing against one another.
Poorly at the first, not at all at the second: that's petrol. Being less viscous than diesel, petrol strips out the protection a fuel system needs, so a pump on the mixture to wear itself. It is also made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the knocking.
Put those together and the shape of the trouble is plain. Not contact but circulation is what causes the damage. Any tank with petrol in it is a fuel issue. After your pump has been running on that petrol, a mechanical fault has started: anything shed by a pump that is wearing down is carried downstream to the fuel injectors with your fuel.
Four scenarios our technicians see around Lakenheath: how serious is petrol in a diesel?
The best case there can be: filled up, never started. The petrol is in the tank and only the tank, and the job is a drain and a flush where the car sits. This is the one situation that can only truly occur on a forecourt, because anywhere else your car has been driven to get there.
Started for a second, or only your ignition on. With the fuel system primed, the fuel lines and filter now contain petrol that came from that tank. That is generally still an easy job — a drain, a flush, and the fuel filter dealt with.
Those few miles driven meant your pump running on fuel weakened by petrol the whole way. How hard the vehicle was driven counts as much as how far, and the work takes in that tank, the lines, the filter and fresh fuel through the whole system. Driving the kids to Lakenheath Community Primary School is one kind of trip. Very different again: a run to Ely, under 15 miles away, or any distance on the M11, under 25 miles from Lakenheath, where your engine kept labouring hard.
Driven on till it protested — rattling, smoke, a ragged idle, a soft throttle. The motor is telling you the fuel is no longer acting like diesel. Stop where you are — on the verge on Wings Road, at the kerb, down a side road — and do not move it. Long-term damage is very rare when a car is pulled over early, and the drain and flush that still go first sort it out.
Lakenheath motorists and that petrol in a diesel myths they hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. Nothing comes out when you top up — the tank simply holds more of the same blend. The assumption behind the advice — that diesel fuel systems accept petrol by percentage — is wrong.
"Current diesels can handle a little petrol" — a myth, and closer to the reverse. Lubrication counts more on newer diesels, not less, since their fuel runs through finer parts at higher pressure.
This is the one that catches drivers. Myth: "If it starts and drives, there's no damage done." Feed diesel to a petrol engine and it normally won't run, so the motorist stops — and the harm stops with them. Feed petrol to a diesel and it usually fires up, idles and drives away as if nothing happened — all the while its pump wears. Fine and running aren't the same at all.
Not so: a two-stroke additive lets you to drive home. It is an old workaround, supposed for another fault. None of what petrol thinned is put back by it — and afterwards, that tank still holds that petrol.
If the engine has run, part of that petrol sits in the filter and the lines, not that tank — and your next start sends it right back through the pump. So the myth "drain your tank yourself and you are sorted" does not hold. Besides, petrol drained into a can by the road is truly risky.
How it happens: petrol in a diesel
A careless moment is rarely the cause, and no one means to do it. The forecourt makes it simple: the petrol nozzle is the narrower 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 slip runs one way.
The moment habit stops matching your car is the moment it takes place. Courtesy car, hire car, or a vehicle that's new. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a well-known forecourt. A train to catch, and a hurried fill en route to the nearest station. A new-to-you diesel Volkswagen Passat, its first fuelling, and a driver accustomed to petrol: exactly when it takes place. With rain, a call coming in, or children to deal with, the hand just does what it has always done.
Next time you fill up around Lakenheath: preventing petrol in a diesel
- Green for unleaded and black for diesel is usual in the UK — yet not on every forecourt. Trust the label on the petrol pump, not the colour.
- Inspect your filler flap. Plenty of vehicles state the fuel inside the flap or on the cap. Look at it on the first fill in any motor you do not know.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of intending to remember, in a household with one of each.
- It sounds silly and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump.
- Tuck your phone away. This is an easy mistake to make while you're thinking about something else.
- Some diesels have a filler designed 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 backstop, not a reason to stop checking the pump.
- Spotting it mid-fill? Stop at once. A thinner mix results from less petrol in that tank, yet your next stage remains the same: do not fire it up.
Already put petrol in a diesel around Lakenheath?
Then the order of things is short. Leave it unstarted, with the ignition switched off as well. Still on the forecourt, at the nearest petrol station or anywhere else? Ask the attendants to help you roll the vehicle clear of the petrol pump. Then call 0333 366 0103 and tell us what got in, roughly how much, and whether it has run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost lubrication, make it a separate fault — Lakenheath has a page all for it.
One petrol in a diesel task around Lakenheath costs more than another. Why?
Four separate tasks lie behind the four scenarios above — which is why there is no fair single price. Which of them you're in is mostly what shifts your cost. The share counts next, meaning how much of the tank is petrol, and then the location of your car and whether reaching it is safe for a technician.
Before any quote, not after, come three questions: the fuel that got in, the volume, and whether it has run. That is why. With those replies, you get a straight figure instead of a range.
About Lakenheath
Lakenheath is a village in Suffolk, situated on the banks of the River Lark at a low elevation of around 11 metres. Lakenheath lies near the border with Cambridgeshire, close to the cities of Ely and Cambridge, and is surrounded by smaller settlements like Undley and Little Eriswell. Lakenheath has a population of approximately 1423 residents, who mostly live in detached houses. Lakenheath is located about 68 miles from London, making it a relatively rural community in the Eastern region.
Fuel drain cover across Suffolk, Lakenheath included
Petrol in diesel calls around Lakenheath — part of the IP postcode area — go to vans that also cover the spots around it, Undley, Little Eriswell and Wangford among them. Our technicians drain where the car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Lakenheath: still at the pump?
Then, you couldn't be in a better place. Leave the car turned off, then ring.