Newham Grange: Put Petrol in a Diesel Car?

Quarter past eight, a hurried top-up on the road in, and it dawns on you at about eleven — by that point your diesel Renault Megane has been parked at Stockton for three hours. Phone us then keep it right where it sits. The journey in is the bit that counts now, as diesel performs two roles on its way through a motor: it burns, and before it burns it protects that high-pressure pump and those injectors. Petrol manages the first and not the second. So those couple of miles were travelled with the pump labouring on a fuel that had lost most of the protection it is built around — which is why the question our engineers ask is how many miles you travelled, not how long the motor has been standing.

Your diesel Skoda Octavia will have felt perfectly ordinary on the way back from St Bede's Catholic Academy. They all do, and that's the snag with petrol in a diesel and not the other way round. Put diesel in a petrol car and it usually will not run, so the driver stops and the wear stops with them. Put petrol in a diesel and it starts, idles and moves off as though nothing has happened — all the while the high-pressure pump does its work without the lubrication your fuel is meant to be providing. Nothing warns you, as from the driver's seat there's nothing to alert you about. Ring us with about how far you travelled and how hard you worked it; the second one counts more than the first.

A diesel injection system works hydraulically as well as chemically: the fuel has to hold pressure, not just burn. Thin that fuel and pressure which should build then stay built leaks past tolerances instead, leaving the motor a poorer, later, less even delivery than it was engineered round. Petrol weakens diesel, and diesel has to be heavy enough to seal the close-fitting components it runs through — that's the entire mechanism. It explains the ordinary Stockton Cricket Club call too: a diesel Dacia Duster that went out without fuss and came back down on power, rough at idle, possibly smoking a little. None of which is the motor failing, and that is the part worth hearing. Your fuel has stopped behaving like diesel. Put your fuel right and it stops.

Three things help when you call from near St Paul's Newtown - A Church of England and Methodist Church Partnership: which side the filler is on, whether our van can pull up next to without blocking the road, and if your engine has run since you filled up. On-street is the most common place our engineers work, so the location itself is rarely the problem — we'd far rather deal with a narrow parking bay than with a car that has been driven to somewhere more handy. We will drain your BMW 1 Series, change the fuel filter where there's a usable one, flush the lines then put clean fuel through the entire system, as by this point the worst of it is resting in the lines rather than in your tank.

Hire car or company car? Ring them before you phone us — some agreements want the hire firm to authorise the work, and sorting that out first is a great deal faster than sorting it later. Then ring us about the Audi A6 near Newtown Community Resource Centre, and do not worry that you can't say how full that tank was. Almost no one can, in a car they collected two days ago, and our engineers work it out on the spot. The reason our technicians ask is that petrol in a diesel does its harm as a share: the same few litres in an almost empty tank is a far stronger blend than in a full one. Petrol is rated on how well it resists igniting under pressure, which is the opposite of what a diesel needs — so the stronger the mixture, the more it rattles, smokes and goes flat.

Newham Grange: broken down where you pulled up

Not everyone gets a sensible spot to pull in. A common call for us instead of an unusual one: realised after setting off, finished up by the verge on Stanhope Road or in a lay-by with the hazard lights flashing.

Whether you sit beside the car or step clear of it rests on if sitting nearby seems sensible. Every mile a diesel obliges you for on petrol drags that blend further into your fuel system — and oblige it often will, which is why your engine doesn't get restarted to limp somewhere handier. Driving on does your car far more harm than a van heading out to an awkward location, and that is no trouble for us.

Where is Newham Grange?

Newham Grange is a suburban area located on the riverside in County Durham, with an elevation of 18 metres above sea level. Newham Grange sits near the cities of Durham and Stockton-on-Tees, with nearby places including Stockton Grange, Grangefield, and Newtown. Newham Grange has a population of approximately 5378 people, predominantly living in semi-detached housing. Newham Grange is situated in the North East region of England, around 217.5 miles north of London.

What a petrol-in-diesel drain will cost around Newham Grange

We can't put one price on this page frankly, since this job is not one job. What shifts it:

• Whether the motor has been started or driven. This is the key one.
• How much of the wrong fuel got in, judged against how much the tank holds.
• AdBlue or unleaded, whichever was put in.
• Where the car is, and whether a van can safely get to and work on it.

Tell us your car, the amount and whether it has run, and you will get a clear answer rather than a range. Not time-critical, with your car at home and going nowhere? Then is fine.

A few litres of petrol in a diesel — too much?

Litres are not the measure. Proportion is, and far more than either, it matters if anything has been run. Five litres in an almost empty tank is a separate situation from five in a full one — but either way, the thing that decides how much work is needed is whether that blend has been sucked through the system.

Is a fuel drain going to void my warranty?

A drain and flush carried out properly is not an alteration and doesn't cancel a manufacturer's warranty. Another good reason to leave it turned off: running a diesel on petrol is the thing more likely to cause a disagreement with one.