Put Petrol in a Diesel Car in St Stephens? Don't Start It
If you have not turned on your engine yet, don't. A fuel drain and nothing else is almost always what a motor needs while the petrol is still inside the tank and the motor has not yet turned over, which is why it's the coming few minutes that count, not how much was put in. Petrol in Diesel comes to your car wherever it has stopped in St Stephens or the rest of Cornwall, on the forecourt, at the roadside or on a driveway, and drains and cleans it there. Call us before anything else begins, so you will see what follows next.
Petrol in a diesel: what to try first
- Never start the vehicle — and never believe it if it starts. That is the part drivers have wrong about petrol in a diesel in particular. A petrol engine given diesel generally just will not run, so the motorist stops and the wear ends with them. A diesel given petrol normally starts, idles and moves off without complaint for several miles. It isn't fine. It is grinding that fuel system whenever you drive.
- Two jobs, diesel: it ignites, and on the way through it keeps your injection pump and injectors lubricated. Petrol only does the one. That is why the car's ignition stays off also — turn it on and you usually prime your system, and that's petrol exiting the tank for exactly those components.
- Don't weaken it. Diesel added on top takes out nothing, so all you get is more of what was already there, because percentage isn't how a diesel fuel system accepts petrol. Super unleaded? Just petrol. The octane makes no difference.
- Stay still if it's safe to. Hazards on, ignition off, keep the car. Wherever you have stopped — the verge on Underhayes Lane, anywhere — an odd location for us is better than a started diesel, and nothing is easier for us to handle than a vehicle that never moved.
- Our van showing up instead of circling depends on two things: a postcode starting PL15 8, and whatever is nearest to you with a label on it. Get both ready before you dial.
- Call 0333 366 0103. Anticipate three things — what went in, approximately how many litres, and whether the motor has been run. The replies settle everything that comes after.
On the forecourt: clearing petrol from your diesel
The job kicks off at a forecourt, typically. Often enough the work wraps up on site too. Still at BP? Then that's generally where it gets done. Station forecourts are normal for us, with the consent of the owner.
Nowhere other than the forecourt can this be halted with your engine still unrun. The few seconds between seeing the till receipt and going for the keys settle how much needs cleaning. Anywhere other than the forecourt — a car park, a driveway, a lay-by — the vehicle was started and moved to get there, so fuel was pulled from that tank, through your filter and into the high-pressure fuel pump. That means the fuel lines and the filter require flushing as well as that tank. It is not a catastrophe, and our engineers can still deal with it where the vehicle is.
Out from the pump, the next customer can get by — so yes, let the staff help you move the vehicle. Worth doing. Shifting the car four spaces does not warrant firing it.
St Stephens and the villages beside it
St Stephens is a residential suburb, and our vans get out to it and to the areas around it on the same rounds: Newport, Lanstephan, St Thomas, Launceston and Chapel.
Not on the list? It tells you nothing. The names above are simply the closest few, and most places around Cornwall have a page of their own somewhere on the site. Contact us and ask instead of assuming, above all where you are on the boundary or anywhere a satnav can't find.
This map marks the area the page spans. The lot is ground our technicians work: a roadside, a forecourt, a private drive, a car park. You never bring your car anywhere.
Each restart primes the fuel lines and pulls more petrol through your filter then into the pump. So a misfuelled diesel Audi A4 on the zig-zags by St Stephens Community Academy is an inconvenience, while the same vehicle restarted three more times to be helpful is a fuel system and not a tank. Somebody will advise you to move the car out of that gateway and deal with it later. Do not. Leave it there, let people moan, then call us.
You drive off at the end, once our engineers have started the car and confirmed it runs smoothly on new diesel, with the system primed. Before that, in the car park by White Horse Inn, the polluted fuel comes out of the tank, your lines get cleaned and the fuel filter comes off where your Ford Focus has a replaceable one. Everything starts with three questions when we reach the car: what went in, how much of it, and whether it has been started since.
Here is the whole process. Diesel needs enough body to seal the tight tolerances it goes through, and petrol takes that away. That is it. Which accounts for the usual Launceston Golf Club call — a diesel Mercedes C-Class, out there without fuss and back down on power, rough at idle, perhaps a bit of smoke. Injection systems work hydraulically as well as chemically, so the fuel has to hold pressure and not just burn; weakened, it bleeds past those gaps instead of building, and delivery comes poorer, later, less even than the motor was engineered around. Not a failing motor, though. Fuel that has stopped behaving like diesel. Put that right and it stops.
Seldom the problem, the spot. On-street is the commonest place our technicians work, and a tight parking bay is far preferable to a vehicle that has been driven somewhere more handy. What does help, when you call from near St Stephen, is three things: the side the filler is on, whether our van can park beside without blocking the road, and whether anything has run since you filled up. Then the BMW 5 Series gets cleared, the fuel filter changed where a usable one exists, the fuel lines flushed and fresh fuel put through the full circuit — because by now the worst of it is in the lines, not that tank.
What takes place next is the issue. Your engine straight away draws the petrol left sitting in the fuel filter and the feed lines back round through your pump a second time, as draining a tank does nothing about fuel that has already left it. Drain it then put new diesel in, a person sure of themselves will tell you — and that advice is half right, as do it to a diesel Skoda Superb parked up, St Thomas the Apostle say, and the thing starts, which is what makes it sound reasonable. Call us instead. Our engineers flush your circuit and take the fuel filter off where the car has a workable one, and that is the difference between the vehicle being put right and your car only starting.
St Stephens: stranded where you stopped
A chance to stop somewhere sensible does not come to everyone. A common call for us and not a rare one: noticed after setting off, ended up on the verge beside St Stephen's Hill or at a lay-by with the hazards flashing.
Out of the car if it is not wise to sit there, beside it when it is. It will frequently oblige. A diesel running on petrol limps along very willingly, and that's the trouble: fire it up to get to somewhere handier and that mixture goes further into the fuel system with every mile covered. A technician heading to a difficult spot is no bother for us, and it is a lot better for the car than pressing on.
A couple of miles on petrol in a diesel: what next?
Here is where your M5 comes into it — under 50 miles away from St Stephens. Some way along, and onto it in the first place: a misfilled diesel will often do both before anything seems wrong. What you get then is seldom a clean stop. Power ebbs away, your idle turns lumpy, and there may be some smoke.
Don't start it to move it. Come off at the first safe exit then switch off. On a longer trip — anything close to the under 25 miles to the closest city — take it the mixture has been through your filter, your pump and the fuel injectors, and say so when you call. It affects what we bring.
A little about St Stephens
St Stephens is a suburban area in Cornwall, situated on the banks of a river and characterised by its terraced housing. St Stephens sits at an elevation of 131 metres, with nearby places including Newport, Lanstephan, and St Thomas. St Stephens is located near the city of Plymouth, which is approximately 21.6 miles away. St Stephens forms part of the wider residential area surrounding the nearby cities.
Once we get to you in St Stephens: what follows
- We find out what got in, how much, and if your engine has run. The replies shape the work, which is why we ask before quoting.
- We clear that tank of the tainted mixture.
- Our technicians purge the lines and clean the fuel filter, so what's left in your system isn't what caused the issue.
- Priming follows, once fresh diesel is in.
- We fire it up and make sure it runs properly on clean diesel.
That has it ready to pull away. Our technicians do everything wherever your car has stopped, which means it never needs to go to a garage, and when it has been caught soon, it is very uncommon for there to be lasting damage.
AdBlue in a diesel tank around St Stephens is a separate job
Never crank it: that first instruction holds whether what went in was AdBlue or petrol. What changes is the fault itself. The protection a fuel system relies on gets stripped away by petrol, which dilutes the diesel. AdBlue? Urea dissolved in water. Tip that in with the diesel and you get corrosion instead, plus deposits.
AdBlue removal in St Stephens has a page of its own with the details on it, including why it is usually the more significant of the two. Our engineers deal with both.
St Stephens prices for a petrol-in-diesel drain
What changes the price is laid out below, because the job is not one job and we can't honestly put a single price on this page.
- Started? Driven? Either answer matters more than anything else on this list.
- Wrong fuel in, against what your tank holds — that ratio.
- Whether it was petrol or AdBlue.
- Where your car is, and whether a van can sensibly get to and work on it.
Tell us your vehicle, the quantity and if it has run, and you will get a clear answer rather than a range. If it isn't time-critical — the car is at home and going nowhere — is fine too.
Petrol in diesel: everyday questions around St Stephens
Fuel drains on a St Stephens petrol station forecourt
Plenty of what our technicians do takes place nowhere else. So yes. Regularly, provided the site consents: another forecourt nearby, plus every other forecourt nearby. Say on the phone where exactly you have stopped. Whether our technicians can work in that location is something our technicians answer there and then.
How much petrol is too much for a diesel?
Whether the motor has run matters a lot more, though the ratio matters too, instead of the litres. An almost empty tank with five litres in it, against a full one with the same five: different situations, certainly. Either way, the work needed comes down to one thing, which is if the fuel system has had that blend drawn through it.
Already driven it with petrol in your diesel? Now what?
Somewhere sensible, then stop, then turn off and keep it off. It's recoverable much more frequently than drivers assume, even though driving is what shifts the trouble from that tank into your pump and injectors — and the single most valuable thing you can do now isn't restart it.
Is a fuel drain going to void my warranty?
No. Carried out properly, clearing and rinsing is no modification at all, and the warranty from your manufacturer is untouched by it. A dispute over a warranty is likelier to come from running a diesel on petrol — so leave it switched off.
Could I put some two-stroke in and just drive?
Two-stroke oil solves a distinct fault, and an old one at that. Nothing it does puts back what petrol thinned. No. That tank still has petrol in it later, and your pump still has to cope with it.
A main dealer for petrol in a diesel — necessary?
Wherever the vehicle is, we drain and flush it there, so a trip to the main dealer does not come into it.
Waiting next to it?
Don't switch your engine back on.
If you have already driven it, pull over somewhere sensible, turn it off and leave it off. Cold, still, going nowhere: that is the best position to be in. Drivers fear this a lot more than they need to.
At the roadside, on the forecourt or at home — on-site fuel draining around St Stephens and across Cornwall.