What to Know About Having the Wrong Fuel in Your Tank

Having fuel in the wrong tank can be a costly and inconvenient mistake. Whether you accidentally put petrol in a diesel tank or vice versa, it’s essential to know what steps to take as soon as possible. 

If you unintentionally put the wrong fuel in your automobile, continue reading to understand the warning signals.

Signs You Have The Wrong Fuel in Your Tank

1. Decreased Engine Performance

Improperly filling the fuel tank with the wrong gasoline or diesel can lead to decreased power output and reduced fuel efficiency.

If too high of an octane rating is used, the fuel will not appropriately combust within the engine, resulting in lower levels of power. On the other hand, if too low of an octane rating is used, the fuel can knock or ping as it combusts, which can drastically reduce engine performance. 

Additionally, incorrect diesel fuel can also cause a decrease in engine performance if it does not meet the manufacturer’s requirements for cetane rating and sulfur content.

2. Increased Exhaust Smoke

This is because petrol and diesel are incompatible and will react when mixed, causing the engine to run poorly. Depending on the severity of the contamination, the issue can range from minor to catastrophic. 

If you accidentally put diesel in a petrol vehicle or vice versa, your car may produce plumes of black or grey smoke from its exhaust pipe. This indicates a problem with your fuel mixture, as diesel cars are designed to burn diesel fuel only, and petrol cars run on petrol only.

3. Car Won’t Start

If you have recently filled up at a gas station and your car isn’t starting, chances are you got the wrong fuel. Diesel fuels are often a different colour than gasoline and may be easier to identify when mixed, but most stations today have separate pumps for each fuel.

What To Do When You Have the Wrong Fuel in Your Tank

Stop Driving 

Stop driving immediately after you have put the wrong fuel in your tank. Doing this will help minimise damage to your vehicle before it gets too severe.

Do not Start Your Engine

If you have already started your engine and noticed the mistake, it is essential to turn off the engine as soon as possible and leave it off until the situation has been resolved.

Call for Help

If you are still trying to figure out how to resolve the issue, call for help instead of trying to fix it yourself. Many professional services specialise in draining and refilling tanks containing the wrong fuel type. They will be able to assess your situation and provide advice on what to do next.

Drain & Refill The Tank

Once the wrong fuel has been drained from your tank, you can then fill your tank with the correct type of fuel. Be sure to check the owner’s manual for the exact type of fuel that needs to be used, as not all vehicles require the same kind of fuel. 


The wrong fuel in your tank can be a severe problem if addressed after a while. Still, thankfully most of the negative consequences can be avoided by taking some simple precautions. Make sure you read the filler cap labels on the side of your car for confirmation that you are filling up with the correct fuel, and always keep your receipts so you can review your last fill-up as an added safeguard. 

If you’ve accidentally filled your tank with the wrong fuel and need to drain the fuel tank, Petron Diesel UK is here to help you! We have been draining fuel for over 12 years and have been in the automotive industry for 20 years. Contact us immediately!