Can Diesel Fuel Damage a Gasoline Engine?

Mixing diesel fuel and gasoline can be a costly mistake, as it can cause significant damage to your engine. Although both diesel and gasoline are combustible fuels, they have very different chemical compositions that make them incompatible with each other. Desperate motorists or those unaware of the risks may think adding a small amount of diesel fuel to their gasoline tank is harmless, but doing so could cost much more in the long run. It’s important to understand the risks associated with mixing these two fuels and any potential remedies for avoiding costly repairs if it does occur.

Differences Between Diesel and Gasoline Engines

Can Diesel Fuel Damage a Gasoline EngineBoth diesel and gasoline engines are internal combustion engines that use a mixture of air and fuel to generate power. Still, they differ in how they deliver this fuel-air mixture into the engine’s cylinders and how they ignite it. In a gasoline engine, fuel is delivered via an electric injector system which sprays pressurized liquid fuel directly into the cylinder at precise intervals determined by the car’s computer system. The spark plugs ignite this mixture at the right time to produce power during combustion. On a diesel engine, however, fuel is delivered via a simpler injection system and ignited by the heat of compression rather than spark plugs.

Risks of Mixing Diesel and Gasoline

Diesel fuel is much thicker and oily in consistency compared to gasoline, making it difficult for it to pass through the fuel injectors found in a gasoline engine. This often leads to clogged injectors which can cause significant damage over time and decreased engine performance due to poor fuel delivery. Additionally, diesel fuel contains higher levels of sulfur which can lead to corrosion in many parts of the gasoline engine, including its valves, cylinders, pistons, and more. As these components become corroded or damaged over time, they’ll need to be replaced at significant cost if you want your car running properly again. Considering the potential damages and the associated repair costs, one might wonder about the price of a comprehensive solution. How Much to Rebuild an Engine can provide clarity on this aspect. Also read about the detailed breakdown of costs, factors affecting the price, and whether it’s worth rebuilding over buying a new engine.

What to Do if You Accidentally Add Diesel Fuel to Your Gasoline Engine

Suppose you’ve accidentally added diesel fuel to your gasoline tank. In that case, there are some steps you should take immediately. Firstly turn off your car’s ignition and wait to start it again until you’ve had a chance to assess the situation further – starting your car could cause serious damage due to improper combustion caused by the diesel fuel. Secondly, get your car checked out as soon as possible by a professional – this will help determine the extent of any potential damage and necessary repairs. Long-term effects of mixing diesel and gasoline fuel can include issues with your engine’s performance, increased emissions, increased noise from the exhaust system, and decreased fuel efficiency due to higher levels of sulfur in the diesel.

How to Avoid Mixing Diesel and Gasoline

Can Diesel Fuel Damage a Gasoline Engine?The best course of action is to avoid mixing these two fuels in the first place; here are some tips for accomplishing that:

  • Make sure you check both pumps and nozzles at the gas station – they should be clearly labeled with “DIESEL” or “GASOLINE” to avoid confusion.
  • Always double-check your tank before filling up – ensure you know which fuel type is in it before adding more.
  • If you’re ever unsure about what fuel you should use in your car, consult your owner’s manual or contact a qualified mechanic who can provide advice based on your car model and engine type.


Mixing diesel fuel and gasoline can cause serious damage to a gasoline engine, leading to costly repairs and potentially reduced vehicle performance. It’s important to understand the risks associated with mixing these two fuels and any potential remedies for avoiding expensive repairs if it does occur. Following the tips above and double-checking your fuel at the pump can help prevent any mix-ups and protect your car from potential damage caused by using the wrong fuel.

Add Comment

Click here to post a comment