Let's leave aside the question of how exactly diesel ends up in a gasoline tank, but it's worth admitting: such mistakes happen quite often.
Fundamental difference
Both the fuel itself and the engines designed for a specific type of fuel have fundamental differences.
During oil refining, fractions are separated at different temperature conditions, which after further processing become:
- gasoline,
- kerosene,
- diesel,
- fuel oil.
Consequently, gasoline and diesel differ not only in chemical composition but also in combustion characteristics: they have different amounts of impurities, and different viscosity, density, and ignition temperature.
Internal combustion engines running on these fuels are also designed differently: in a gasoline engine, the air-fuel mixture enters the cylinders and ignites from an electric spark. The key feature of diesel (among many other differences) is that the mixture heats up and ignites due to strong compression in the cylinder.
Diesel in a gasoline engine
In a gasoline engine, the pressure of mixture supply to the cylinders is significantly lower than that required for diesel fuel ignition. Therefore, while there is still some gasoline left in the system, the combustion process changes dramatically: diesel burns incompletely, leading to intensive soot formation.
Diesel entering the fuel lines of a gasoline car leads to their clogging. There is a high probability of diesel penetrating into the crankcase through the cylinders, which will ruin the engine oil.
When the gasoline supply runs out, the engine will simply stop.
Consequences:
- cleaning and repairing the engine, at least the cylinder-piston group,
- cleaning and repairing the fuel system and injectors,
- replacing the fuel filter,
- replacing the oil.
By the way, carburetor engines tolerate contact with diesel somewhat easier than injection engines.
Gasoline instead of diesel
Gasoline has much worse lubricating properties (fuel equipment parts are lubricated by oils contained in diesel fuel), it has different thermal conductivity and a different combustion pattern.
A diesel engine can run on unsuitable fuel longer than a gasoline one. But the damage can be more serious: insufficient lubrication and a different temperature regime lead to overheating of the unit and can even cause its destruction.
As a result, if the engine is repairable at all, a significant part of its parts will have to be replaced.
First steps
Even after filling with the wrong fuel, some amount of the "correct" fuel remains in the lines. Therefore, if you make a mistake at the gas station and fill diesel into a gasoline car, you can drive some distance, but throughout this journey the engine will receive damage, sometimes irreversible.
A similar situation occurs with a diesel car whose tank gets gasoline, with the difference that the diesel engine will most likely continue to work until it critically overheats or is turned off.
Therefore, if you notice a mistake at the gas station, it is strictly forbidden to start the engine — this way you will save both the engine itself and the fuel system.
It is better to call a tow truck or tow the car to a service center, where they will drain the fuel and flush the tank. For gasoline cars, flushing the tank is especially important, while a diesel engine is more tolerant of small gasoline residues.
What's next
Repair costs directly depend on how badly the engine is damaged: from minimal damage (when it is enough to flush the tank and system) to a complete engine replacement.
Typically, the list of works looks like this:
- draining fuel and cleaning the fuel tank,
- flushing the fuel lines,
- installing a new fuel filter,
- cleaning injectors, replacing spark plugs,
- replacing oil and oil filter.
1 - fuel tank; 3 - expansion box; 4 - filler neck plug; 5 - fuel level sensor; 6 - supply fuel line; 7 - return fuel line; 8 - fuel filter; 9 - fuel pump; 10 - mesh filter; 11 - fuel pump housing, 12 - pressure accumulator; 13 - protective pan; 14 - adsorber
Not all is bad
Diesel in a gasoline car is a real disaster for the engine, but the reverse situation is simpler. If a diesel engine is provided with sufficient lubrication (for example, by adding oil to the tank), it can run on gasoline for some time without serious damage. Of course, after such a procedure, the fuel line still needs to be flushed.
Moreover, for some diesel cars in cold weather, it is even recommended to add gasoline to the tank. The proportion of added gasoline depends on the air temperature and can be up to 5% and even up to 25% of the total volume.
Conclusion
If the tank is completely filled with the "wrong" fuel — do not try to start the car! In this case, you might get away with just flushing the tank and fuel system.
A gasoline engine cannot run on a mixture with diesel. So there is no point in diluting a full tank with gasoline.
A diesel engine, on the contrary, can run on fuel with a gasoline admixture (preferably no more than 5%). So if there is a little gasoline in the tank, you can simply dilute it with diesel, and this will not greatly affect the engine's operation.
