Wrong Fuel in Your Car: What to Do About Misfuelling in Glasgow

You are standing at a pump with a sinking feeling. You have put the wrong fuel in, and you are trying to work out how bad this is.

The honest answer is that it depends almost entirely on one thing: whether you have started the engine. Everything else is secondary.

If you have not started the engine

Good. This is the cheap version and it stays cheap as long as you do not touch the ignition.

Do not start the engine. Do not turn the key to the position that wakes the dashboard either, because on many modern cars that runs the fuel pump for a couple of seconds to prime the system, and that is enough to pull the wrong fuel out of the tank and into the lines.

Do not put the car in gear or attempt to move it under its own power.

What to do instead: put the handbrake on, put it in neutral, tell the forecourt staff, and get help pushing it clear of the pump to a parking bay. Then call for a fuel drain.

The job is a straightforward one. The tank is drained, the system is flushed through, the correct fuel goes in, and the car drives away. It is usually done at the roadside or on the forecourt in under an hour, and the cost is a fraction of the alternative.

If you have started the engine

Stop as soon as it is safe. Every additional minute of running makes this worse.

Pull over, switch off, and do not restart to move it a bit further along. Then call for recovery rather than a drain, because the car now needs a workshop.

How bad it is depends on which way round you have done it.

Petrol in a diesel is the serious one and it is by far the more common mistake, because a petrol nozzle fits easily into a diesel filler neck while the reverse generally does not.

Diesel is an oil. It lubricates the high pressure fuel pump, the injectors and the seals throughout the system, all of which run at extreme pressures with clearances measured in microns. Petrol is a solvent. It strips that lubrication out, and the pump begins wearing itself apart within minutes, sending metal particles downstream into the injectors and the rail.

Caught immediately, it is a drain and flush. Run for a few miles, and you are potentially looking at a new high pressure pump, injectors, rail, filter and lines, which on a modern common rail diesel is a four figure bill and can approach five.

Diesel in a petrol is generally less destructive. Diesel will not ignite properly from a spark, so the car typically runs badly, misfires, produces white smoke and then stops. The damage is usually limited to fouled plugs and a system that needs draining, though catalytic converters and lambda sensors can suffer if it is run for long.

Either way, the instruction is the same: stop, do not restart, call.

The cost, plainly

A roadside fuel drain on a car that was never started: typically a few hundred pounds all in.

Recovery plus a workshop drain after a short run: more, but still recoverable.

A full fuel system replacement after driving on petrol in a diesel: often between two and five thousand pounds depending on the vehicle, and considerably more on some premium models.

That is the entire reason this article exists. The difference between the top and bottom of that range is whether you turned the key.

Will insurance cover it

Sometimes, and it is worth checking rather than assuming.

Misfuelling is excluded from most standard motor policies as driver error, though a growing number of comprehensive policies and some breakdown products include it as an optional extra. If you have any form of add on cover, check the wording before paying out of pocket.

If the wrong fuel went in because forecourt equipment was faulty or mislabelled, that is a different conversation and photographs of the pump are worth taking.

How to not do it again

The common threads in the misfuelling jobs we attend are a recent change of car, a hire or courtesy vehicle, a company van the driver does not usually drive, distraction, and being in a hurry.

Practical defences: a coloured cap or a label inside the filler flap on any newly acquired car, reading the nozzle rather than reaching by habit, and a diesel misfuelling prevention device if you have swapped from petrol to diesel and keep almost doing it.

If you drive several vehicles, check before every fill rather than trusting muscle memory.

Calling us

SRL Recovery handles misfuelling across Glasgow, Lanarkshire and Renfrewshire, twenty four hours a day. We carry out mobile fuel drains where the engine was never started, and we recover to a specialist where it was.

Ring 01698 700970 and be straight about whether the engine has run and for how long. It is not a judgement, it is the information that decides which truck comes out and what happens when it arrives.

Quick answers

I put the wrong fuel in but did not start the car. What now? Leave the ignition completely alone, push the car clear of the pump, and call for a fuel drain. This is the cheap outcome.

I drove a few miles before realising. Is the engine ruined? Not necessarily, but stop immediately and do not restart. Petrol in a diesel does progressive damage the longer it runs.

Is diesel in a petrol car as bad? Usually less serious. The car tends to misfire and stop rather than destroy the fuel pump, but it still needs draining.

Can you drain the fuel at the roadside? Yes, where the engine has not been started. If it has been run, the car goes to a workshop instead.