What Happens If You Put Gas on a Diesel Engine?

What Happens If You Put Gas on a Diesel Engine?
Diesel engines depend on the lubricity of the diesel to run well. Find out what happens if you put gas in a diesel truck and how to fix it🚛.

What Happens If You Put Gas On A Diesel Engine and How To Fix It?

As a diesel truck owner, at some point you may have wondered what happens if you put gas on a diesel engine. Even if it has never happened to you, the risk of making this small mistake is always present. Whether it's because of a long trip, a distraction, or because the labels at the station are unclear, it's a scary scenario.

No matter the cause, in a few seconds this error can be a catastrophe for the injection system. At RoadPro we care about keeping our customers informed. Read on to find out what happens if you put gasoline in a diesel truck and how to fix it.

What is the difference between gasoline and diesel?

Both gasoline and diesel are petroleum products used as fuels. It is therefore logical that the question arises as to what happens if you put gasoline in a diesel engine. The choice between gasoline or diesel usually depends on the type of truck and the desired performance.

However, their compositions, physical properties and uses in engines are different. Let's see:

Composition and Origin

Gasoline: A liquid fuel derived mainly from crude oil through refining processes. It contains light hydrocarbons, such as alkanes, alkenes and aromatics.

Diesel (or Gasoil): It is also a liquid fuel derived from crude oil, but is obtained from heavier fractions during the refining process. It contains heavier hydrocarbons than gasoline, including alkanes and some aromatic compounds.

Physical Properties

Gasoline: Tends to have a lower density and higher volatility compared to diesel. This means that gasoline evaporates more easily at lower temperatures.

Diesel: It is denser and less volatile than gasoline, which means that it tends to evaporate more slowly.

Uses and Engines

Gasoline: It is mainly used in gasoline engines, which are common in automobiles, motorcycles and some small engines such as lawn mowers.

Diesel: Used in diesel engines, which are common in trucks, buses, diesel cars and heavy machinery. Diesel engines tend to be more fuel efficient than gasoline engines.

Differences Between Diesel Engine And Gasoline Engine

Both diesel and gasoline engines  run on internal combustion. That is, they burn the fuel, which provides the power for the vehicle to move. The difference between the two engines lies in the behavior of the fuel in the ignition chamber.

Diesel acts as a power source and as a lubricant for the fuel injector and other parts of the combustion system.  Diesel engines burn fuel at high pressure. That is, they compress the air before injecting the fuel, which raises the temperature and ignites the diesel fuel without the need for a spark.

How to Remove DEF Fluid from the Diesel Tank

Gasoline engines  on the other hand, require the spark plug to ignite the gasoline. This is because gasoline is more liquid and needs a spark to ignite.

What Happens If You Put Gas On A Diesel Engine?

Diesel is an oil-based fuel that also serves as a lubricant. Gasoline, in addition to being a fuel, functions as a solvent, which is a major drawback for a diesel engine.

We explain in detail what happens if you put gas on a diesel engine:

Ignition System

Diesel engines use air compression to ignite the fuel, while gasoline engines use sparks generated by spark plugs.

Gasoline has a low ignition temperature. If gasoline is used in a diesel engine, it is likely to ignite prematurely due to high air compression in the cylinder. This can result in violent knocking and engine damage.

Lubrication and Sealing

Gasoline has different lubrication properties compared to diesel. Diesel engines depend on the lubricity of diesel for proper operation of injection pumps and other components. Gasoline can have an adverse effect and reduce the lubricity of the fuel system.

Component Damage

Gasoline can damage diesel fuel system seals and gaskets. This happens because diesel engines are not designed to handle the solvents present in gasoline. This can lead to leaks and other problems in the fuel system.

Inadequate Performance

The combustion of gas on a diesel engine can cause a significant loss of power and temperature rise. In addition, additional problems may arise that affect the truck's performance.

truck refeer.

Best and Worst Case Scenarios

If you are wondering what happens if you put gasoline in a diesel engine, you should evaluate certain actions to know the seriousness of the issue. For example, a very important factor is whether you started the engine or if you realized the error while filling up. If you did not start the engine, the damage will be minor.

If you fill the tank completely with gasoline and drive with it, a reaction known as engine seizure will occur. In addition,  the high pressure and temperature of the diesel engine will cause the gasoline to detonate. This will damage the anti-pollution systems and cause extensive damage to the injection system elements.

Note that this is the worst-case scenario, and will only occur if there is any diesel left in the tank. 

If there is only gasoline, the engine will not start, since diesel engines do not produce the spark that gasoline requires to explode.

There is an intermediate scenario in which the amount of gasoline does not exceed 15%. The truck will start, jerk a few times and make strange noises, causing damage to the fuel pump and injectors.

In case the amount of gasoline in the diesel engine is over a quarter of the tank, the truck will start, but will stop instantly.

What To Do If You Put Gas In A Diesel Engine?

The main thing is not to start the vehicle with the wrong fuel. As we have just mentioned, starting the engine will only make things worse, resulting in breakdowns and higher costs.

Here's what to do if you put gasoline in a diesel engine:

  • If you notice when refueling, do not start the truck and do not insert the key in the ignition. This will prevent the low-pressure fuel pump from starting and sending gasoline into the circuit.
  • Make the service station personnel aware of the situation. They will then implement their contingency plan, close the area and inform the rest of the drivers. 
  • Call a roadside assistance service to send help immediately. Calls are prohibited in the assortment areas, so you must go to a safe place to do so.
  • Once help has arrived, the specialists will empty the tank, clean it and replace the fuel filter. They will also evaluate the injectors, injection pump and fuel rail. 

Leave The Work To Professionals

If you are in a hurry and do not have the necessary knowledge, do not attempt to empty the tank yourself. Make sure that your reliable workshop has a truck equipped to provide roadside assistance for diesel engines. This way you will be able to get your truck up and running without taking a detour and save time.

When these types of accidents occur, in addition to wondering what to do if you put gas in a diesel engine, you want to fix it. If you or an unqualified person tries to fix the problem, you run the risk of generating other breakdowns. For example, you may risk dealing with a ruptured hose near the fuel filter.

On the other hand, extracting fuel from a truck is a risky activity that requires safety measures. Among these are the use of special clothing, signaling on the road, grounding and other necessary actions to carry out the protocol.

Gasoline is a highly flammable substance. If you try to remove the fuel without using the proper technique, you may cause a spill. Remember that you are in a gas station, so the risk of fire or explosion is higher.

Contact us now!


If you need help from expert mechanics, RoadPro is your best choice for emergency roadside assistance. We have diesel engine specialists who will fix this issue. We are located in Atlanta and cover up to 100 miles around the city.Contact us at 470-750-2555 or info@roadproassistance.com. We offer assistance 24 hours a day, 365 days a year. Our professionals will provide you with specialized attention and free quotes, call us now!