Spotland Bridge: Petrol in a Diesel Car? How Worried to Be
Likely less than you already are — as long as no one has started the vehicle. Till the ignition primes your pump, your starter cranks, or the vehicle is driven, petrol in a diesel tank just sits there and does nothing. Which makes the honest reply to the first Spotland Bridge question — "have I wrecked it?" — normally no. Petrol in Diesel is who to call, with your engine left off, so it remains that way. What petrol really does to a diesel, how to judge how far it has gone, and how to stop it from happening again: that is the remainder of this page.
Petrol in a diesel: what does it do to your engine?
Passing through a motor, diesel does two jobs at the same time. It ignites, and before it combusts it lubricates. The high-pressure fuel pump and your injectors are made to very fine clearances, and the diesel passing through them is what keeps those surfaces from wearing down against each other.
The second job petrol does not do at all, and the first it does badly. A pump working on a petrol mixture is wearing itself out, because petrol is runnier than diesel and takes away the lubrication the fuel system relies on. Petrol is also made to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that is where the rattling starts.
Put these together and the shape of the issue is plain. Not contact but circulation is what does the damage. All a tank with petrol in it amounts to is a fuel issue. Whatever a worn pump sheds goes on, carried by your fuel, into the fuel injectors further along, which is why a pump that has worked on that petrol is where a mechanical fault begins.
Four scenarios our engineers see in Spotland Bridge: how bad is petrol in a diesel?
Filled up, and not started: no case is better. On a forecourt, and genuinely only there, the petrol is still limited to the tank — because everywhere else your car was driven to reach it. The job is draining and purging on the spot.
Started for a moment, or just your ignition on. Petrol has left the tank and reached the filter and the fuel lines, because the fuel system has been bled. Normally little more than emptying, purging and sorting your filter, so still simple.
Some miles driven, and the pump has spent every one of them working on weakened fuel. The work is that tank, the lines, the fuel filter and clean fuel through the whole system, and how hard your car was driven matters as much as how far. The school run to Spotland Primary Academy is one matter. A run as far as Manchester, under 15 miles away, is a very different task. So is any mileage on the A627(M), under 3 miles from Spotland Bridge, where the motor has been labouring hard the whole time.
Rattling, an uneven idle, smoke, a throttle gone soft: driven until it complained. The motor is telling you your fuel is no longer acting like diesel. Pull up on the spot — on the verge on Spotland Road, at the kerb, down a side road — and don't move it again. What goes first is still the drain and flush, and that deals with it, with lasting damage very rare if a vehicle is pulled over soon.
What Spotland Bridge drivers get told about petrol in a diesel — and the myths in it
Myth: topping up to full with diesel makes it fine. It does not. Nothing comes out when you top up — the tank simply holds more of the same mixture. That advice assumes a diesel fuel system tolerates petrol by percentage. It doesn't.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. Finer parts and higher pressure are the way a modern diesel runs its fuel, and that makes the lubrication count more, not less.
One myth that catches people off guard: if it starts and drives, it must be unharmed. The driver of a petrol engine fed diesel normally has no choice but to stop, because it will not run, and the harm stops there. A diesel fed petrol usually starts, ticks over and drives away as though nothing has happened, whilst the pump wears. Running isn't the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a different fault. It does not put back what petrol has thinned, and the petrol is still in your tank later.
Myth: "Drain that tank yourself and you are sorted." After your engine has run, some of the petrol is no longer in that tank: it is in the fuel filter and the lines, and it goes straight back through the pump at your next start. On top of that, petrol cleared into a can by the road is truly dangerous.
Why petrol in a diesel occurs at all
It's rarely carelessness, and nobody does it on purpose. One way only, since of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one generally will not fit a petrol car. That is how the forecourt makes it easy.
The moment routine stops matching your car is the moment it takes place. A new motor, a hire car or a courtesy car. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a familiar forecourt. Rushing for a train at Rochdale and fuelling up en route. Years of petrol vehicles behind you, a diesel Volkswagen Tiguan in front of you on 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.
Spotland Bridge drivers: how to avoid petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Read the petrol pump's label; the colour is just a clue.
- The first fill in a strange car is the time to check the filler flap — on it, or on the cap, plenty of motors state which fuel to use.
- Label the key. In a household with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- It seems daft and it works: on your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump.
- Mistakes like this are simple to make while your mind is on something else, and so your phone goes away.
- Add-on devices exist for cars without one, and some diesels come with a filler that won't take a petrol nozzle. Useful — but a backstop at best, never a reason to stop checking the label.
- Stop as soon as you realise. Less petrol inside that tank means a thinner mix. It doesn't change what to do next, which is still not to fire it up.
Put petrol in a diesel around Spotland Bridge already?
Short and simple, then, is the order of things. Leave it unstarted, with your ignition off too. Ask the attendants to help you roll it away from the petrol pump if you're still on the forecourt, whether that's Asda or somewhere else. What was put in, about how much, and whether it has run: tell us that when you call 0333 366 0103.
If it was AdBlue rather than petrol, say so. That is a separate fault — corrosion and deposits rather than lost lubrication — and it has its own page for Spotland Bridge.
One petrol in a diesel job in Spotland Bridge costs more than another. Why?
The four scenarios above are four separate tasks, so no single quote for this would be honest. The scenario itself does most of the work of moving your cost. Two things come after that: the petrol that was put in as a proportion of what the tank takes, then the spot your car is in and whether our van can get to it safely.
Three questions come first, before any quote, rather than after — what was put in, how much, has it run — and that is the reason. Their replies are what turn a range into one firm number.
About Spotland Bridge and where it is
Spotland Bridge is a suburban area in Greater Manchester, situated near the River Roch and close to the towns of Rochdale and Bury. Spotland Bridge sits at an elevation of 146 metres, with its terraced housing stock reflecting the local architectural style. Spotland Bridge is located near several other residential areas, including Spotland Fold and Caldershaw, and is around 10 miles from Manchester city centre.
Spotland Bridge and Greater Manchester: where our fuel drain cover runs
Petrol in diesel call-outs around Spotland Bridge — part of the OL postcode area — go to teams that likewise cover the places about it, Spotland Fold, Greave and Caldershaw among them. We drain where the vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Spotland Bridge: still at the pump?
Then you are in the best spot there can be. Switched off it remains; then call.