Car Talk: Gas-Diesel Switch Isn’t Fatal, But It Is Costly


Gas-Diesel Switch Isn't Fatal, But It Is CostlyWith the increasing popularity of diesel-fueled cars, many gas stations are starting to place diesel pumps among the gasoline pumps. As such, some people put diesel into the gas tank of a gasoline car by mistake and only realize when it is too late. Others put regular gas into the tank of a diesel vehicle. The good news is that, the damage can be reversed, but it is something that should be avoided as much as possible.

This confusion is not something that happens every day. Car fuel tanks are clearly labeled to separate gas from diesel tanks. Diesel tanks are always labeled “diesel” to try and reduce any mix-up. In most cars, diesel tanks are always green. Therefore, before making that mistake, most people will notice that difference and adjust to the correct fuel in time.

However, despite all the efforts to differentiate the fuel tanks, it is something that happens quite often. Sometimes people get too busy or distracted and fail to realize they are putting fuel in the wrong tank. Some might be talking over the phone, fighting with the kids, or replying text messages. Those distractions are enough to create that confusion.

When diesel ends up in the wrong tank, meant for gasoline, the car will run normally for a short distance. The gasoline gets used up and the car will shut down. The car will shut down because gasoline engines cannot run on diesel. They have not been designed to burn diesel since their combustion system is totally different.

The car will then have to be towed to a repair shop once that has happened. The mechanics will have to drain the entire fuel system to remove any traces of diesel. The process starts with emptying the gas tank. This is then followed by cleaning the diesel from the fuel lines, injectors and fuel rails.

The most common solution is using fuel injector cleaner to fix the problem. However, that may not work sometimes which calls for taking things apart and checking them individually. The good news is that there is no permanent damage on the seals and injectors. Furthermore, chances are very minimal for damage to occur on the catalytic converter since the car would not have run on the diesel.

The main problem involved is that it can be a costly and time consuming affair. The procedure would normally cost $500 to $1000 depending on the model of the car. There are some mechanics that purport to charge less than that. As much as they will solve the problem for the moment, future issues might arise which might take up more money. Therefore, it is advisable to seek the services of a proven professional.

Gas-Diesel Switch Isn't Fatal, But It Is CostlyOn the other hand, putting gasoline in the diesel tank by mistake can prove to be more problematic based on the quantity of gasoline that has been added. If it is a 20-gallon tank, and the gasoline that has been put by mistake is 1 gallon while the rest is diesel, then that is only a small matter to solve. If it is beyond that, then it becomes a serious problem.

Diesel is also a lubricant, apart from being the fuel of the car. Therefore, the fuel injector pump does not receive sufficient lubrication when a diesel engine is run on gasoline. Also, gasoline and diesel have different combustion properties. Therefore, gasoline will tend to detonate much earlier than the diesel in diesel engines that have a high compression. When this happens, it leads to misfiring and knocking which can be very grave damages on the engine.

For the mistake to be corrected, other parts of the engine will have to be replaced, on top of draining the fuel tank. As indicated earlier it will cost more to deal with putting gasoline in a diesel tank than putting diesel in a gasoline tank.


Refueling a car is an important job that should not be done when one is distracted or in a hurry. Mistakes happen all the time, but gasoline is a highly flammable liquid that calls for utmost care and handling. With the huge costs involved due to a simple lapse or distraction, public education is needed to inform the public about such occurrences. Gas stations should lead such campaigns and also place notices in areas where they can be seen by everyone going to refuel.