Both are bad but one is definitely worse. Putting the wrong fuel in your vehicle can lead to breakdowns, repairs, and a lot of frustration. However, the impact of diesel in a petrol car versus petrol in a diesel car is very different.
If you’ve ever wondered which mistake causes more damage, this article breaks down the science, symptoms, and solutions behind both.
Diesel in a Petrol Car
Let’s start with the less catastrophic of the two. Petrol engines rely on spark ignition, while diesel is much thicker and ignites differently. When diesel enters a petrol engine:
- It doesn’t burn efficiently, leading to smoke and stalling.
- It clogs spark plugs and injectors.
- It can damage the catalytic converter over time.
Typical symptoms include:
- Difficulty starting
- Jerking or hesitation when accelerating
- Black smoke from the exhaust
While inconvenient, this mistake is usually fixable with a professional fuel drain if caught early.
Petrol in a Diesel Car
This is the mistake you really want to avoid. Diesel engines depend on the lubricating properties of diesel fuel to keep their components running smoothly. Petrol, on the other hand, acts as a solvent, it removes that lubrication and increases friction.
Once the engine is started, damage can occur almost immediately.
You might experience:
- Metallic knocking noises
- Sudden loss of power
- Engine failure or complete shutdown
This type of misfuelling often leads to injector or fuel pump damage, which can cost thousands to repair.
Which Is Worse?
There’s no contest, putting petrol in a diesel car is far more damaging than the other way around.
Diesel engines are more sensitive to fuel quality and rely heavily on lubrication. Even a small amount of petrol contamination can lead to costly repairs or full engine replacement.
Why Early Action Matters
The good news? Most misfuelling cases can be resolved without permanent damage if you act fast. The key is not starting the engine and calling a professional fuel drain service immediately.
At Wrong Fuel Recovery & Mobile Mechanic, we’re available 24/7 across Australia to handle both types of misfuelling incidents safely and efficiently.
How We Fix It
- We arrive at your location, no towing needed.
- Drain the contaminated fuel completely.
- Flush the fuel lines and tank.
- Refill with the correct fuel.
- Check your engine to ensure it runs smoothly.
In under an hour, we can get most drivers back on the road.
Preventing Misfuelling
Avoiding this headache is easier than you think:
- Double-check the fuel nozzle before filling up.
- Add reminder labels near your fuel cap.
- Avoid distractions, especially when driving different vehicles.
- Teach all drivers in your household the correct fuel type.
Both types of misfuelling are serious, but petrol in a diesel car poses the greatest risk to your engine. The best protection is prevention and fast professional help if it happens.
If you ever find yourself in this situation, don’t panic and don’t start your car.
Call Wrong Fuel Recovery & Mobile Mechanic at 0422 987 222, we’ll drain, flush, and refuel your vehicle quickly so you can drive away worry-free.