Wrong Fuel in Diesel Engine: What to Do

//Wrong Fuel in Diesel Engine: What to Do

Wrong Fuel in Diesel Engine: What to Do

A borrowed car, a rental car, or a simple mistake, it can happen that everyone has the wrong fuel when it comes to refueling.

Gasoline in diesel , diesel in gasoline?

Engine ruined?

Risk of explosion?

It all depends on the “mixture” created and the base fuel of the vehicle.

Getting the wrong fuel is a common mistake. Especially when changing vehicles. Even more, to complicate our life, the color of the pistols sometimes varies from one station to another.

Whatever the case may be, a moment of inattention and it’s too late, the damage is done. So how do you react when this happens?


ATTENTION: Explosive mixture!
The gasoline-diesel mixture is highly flammable, so any handling of the mixture must be done with the greatest care. So, no need to play with fire trying to drain or siphon the tank yourself. Rather, call a professional, it is the smartest thing to do in this situation.

What Happens if Diesel Engine is Filled with Gasoline or Petrol?

It is human error, but when it comes to confusing diesel and gasoline, the consequences can be dramatic for the car engine . Indeed, the cleaning power of gasoline undermines all the work of lubricating diesel by destroying the protective film necessary for the proper functioning of the diesel injection system. When gasoline fuel is mistakenly mixed with diesel fuel, the engine burns the diesel fuel first before quickly gasping and rattling under the hood.

How terrible is the mistake of putting gasoline in a diesel engine ?

Of all the scenarios, this is the worst.

Here’s why: Gasoline has a degreasing power while diesel has a lubricating action. In short, they do exactly the opposite of each other!

Result: As we explained above, gasoline completely undermines the work of lubricating diesel, destroying the protective oily film of the engine’s injection system. Suddenly, your poor engine will suffocate and start to cough. You will hear a clicking noise under the hood and engine failure is guaranteed. We’re not going to lie to you, it’s not good at all! If the system is badly damaged, it can have fatal consequences for the engine.

Good news: The picture is not so dark in all cases. Indeed, if you realized your mistake from the very beginning of the filling at the pump, you may be saved. But if and only if you have only put a few drops of gasoline (max 3% or 10%, depending on the engine) in your tank. Then you just have to fill the rest of the tank with diesel to sufficiently dilute the gasoline.

This is a risky solution. However, how can you be sure of not having exceeded the fateful threshold?

Our advice: Don’t play the sorcerer’s apprentice and always have your tank emptied, it’s safer.

Fuel Error: What to do

To stop this mechanical “asphyxia”, it is necessary to:

  1. Immediately stop the engine;
  2. Perform an emptying.

If the error is noticed while the car is still stopped at the pump, it is essential not to start the engine. Because it takes little to damage a diesel engine. The maximum rate of gasoline allowed is 15% in winter, 10% the rest of the year, and only 3% for new common rail diesel (HDi, DCi, etc.). Beyond that, emptying is essential.

Who Can Perform Fuel Tank Emptying?

Service stations are sometimes equipped to perform a fuel tank emptying, at the cost of a full tank, and a few hours of labor. Otherwise, it is better to call a repairer, because a fuel tank drain cannot be done without certain precautions. The gasoline/diesel mixture is highly flammable.

What Happens if Gasoline or Petrol Engine is Filled with Diesel?

Putting diesel instead of gasoline is less harmful than the other way around. However, we must still avoid making a mistake. Note that the maximum rate of diesel allowed in a gasoline vehicle is 10%.

Below this threshold, your car may produce a little smoke and jerkiness.

Beyond this threshold, however, the consequences can be more serious.

In all cases, it is strongly recommended to contact a mechanic to have the tank emptied.

How terrible is the mistake of putting diesel in a gasoline or petrol engine?

Fortunately, this is hardly possible anymore. Because recent cars that run on unleaded fuel have a tank sleeve whose diameter is smaller than that of the pump gun.

As for older cars (not catalyzed), you will also need to go through the draining step if you put more than 10% diesel in your tank. Below this limit, your car will smoke and gasp, but then it should run normally. Provided that you do not pull on the engine and that you regularly top up gasoline to reduce the proportion of diesel in the tank.

This is a risk to take, especially since it can impact the performance of the engine. If in doubt, have your tank drained, if possible before starting the vehicle.

When Should You Drain Your Fuel Tank?

Beyond these two most common fuel errors, you could also make the mistake of putting unleaded 95 in an old petrol car. It is necessary to top up quickly with unleaded 98 to prevent the engine from rattling.

Or you may think you put diesel in a catalyzed petrol car. But putting diesel in a catalyzed petrol car is impossible, the diesel gun being of greater diameter than that of the orifice.

ford truck diesel repair and services

What is Covered by Your Insurance?

Not only does your vehicle run the risk of being damaged as a result of putting diesel in a gasoline engine, but also the emptying of a tank following a fuel error has a price.

Not to mention the costs associated with towing your vehicle or the need to find a rental car following a fuel error.

Fortunately, these various expenses can be covered by your car insurance, provided that you have taken out an assistance guarantee.


Important things to note so you act fast if this ever happens:

1. Do not start the engine while you are still at the pump

2. If you’ve already started the engine, immediately pull over and shut off the engine

3. Call a reliable diesel engine technician to have your tank emptied

4. If there is no other damage, refuel. But with the right fuel this time.

By | 2020-11-02T10:45:04+00:00 November 1st, 2020|Diesel Engine Maintenance|0 Comments

About the Author: