Kieran is on his way home from work, exhausted after a long day. He’s been rushing to meet a project deadline, and now that it’s in the bag, he can’t wait to get home. To save himself hassle in the morning, he stops at a filling station to fill up. Just as he’s replacing the pump, he realises to his horror: he has put petrol in his diesel engine. Instead of tearing his hair out, he phones a petrolhead friend for advice.
What to do
If you ever make this mistake, act quickly.
- Whatever you do, do NOT start your vehicle. Switching on the ignition will circulate the mixture of petrol and diesel through the fuel system. This contaminates other components.
- Call your mechanic. Explain the situation. Tell them the exact quantities involved. Each case is different; the age, condition and engine are crucial factors in determining how serious it is.
- If your mechanic recommends bringing the vehicle in, have the vehicle towed to the garage. To fix this problem, the tank will need to be drained.
- At the garage, the mechanic will drain the petrol from the fuel system, and if needs be, replace the fuel filter or maybe even the fuel tank.
- The mechanic will then safely dispose of the petrol.
The dangers of putting petrol in a diesel car
- Putting petrol in a diesel car causes severe engine damage to the injectors, which can be expensive to fix.
- Due to the difference in lubricity, fuel system damage is inevitable when petrol is run through a diesel system.
- Because they have different combustion points, engine damage is likely to result. In extreme cases, the engine may blow up.
- If the engine has been started with petrol, it will eventually stop running. This may result in further damage to the vehicle’s emission system.
- If you've noticed your mistake after a litre or two, simply fill up the rest of the way with diesel and use a diesel-specific additive for protection. If you've filled the whole tank, your only recourse is to drain it completely or risk substantial fuel system and engine damage.
The effects of misfuelling
- Diesel fuel pumps are lubricated by the diesel fuel itself. Mixing petrol with diesel creates a solvent, which means it reduces lubrication and can damage the pump through metal-to-metal contact.
- The more contaminated the system becomes, the more expensive it will be to repair. In extreme cases, it can be cheaper to fit a new engine.
How to prevent misfuelling
It’s easy to say the best way to avoid misfuelling is simply a case of always filling your tank with the correct fuel. However, mistakes are made. When we’re tired, we’re easily distracted. Here are some tips to reduce the risk of misfuelling:
- Always read the pump’s trigger label and the fuel grade indicator.
- If you’ve bought a new car and it has a different fuel engine than your previous car, leave yourself reminders in the car. A simple note on the dashboard that reads ‘Diesel, NOT Petrol’ is enough to stop you reaching for the wrong pump.
- When you’re at the petrol station, get rid of all distractions. Get off the phone; don’t chat to your passenger while you’re at the pump. It only takes a few minutes to refuel so give the task your undivided attention.
- If you’re hungry and can’t stop thinking about lunch, do not refuel the car. If you’re late collecting your kids from school, do not refuel the car. If you’re stressed about a meeting, do not refuel the car. When we’re hungry, in a hurry, or stressed, our minds are elsewhere and we’re more likely to make mistakes.
Around 150,000 UK motorists make this slipup each year; that's one every few minutes. When you stop at a petrol station to refuel, keep your mind on the task at hand. Filling your car with the wrong fuel can be a very expensive mistake!