Will a Little Gas Hurt a Diesel engine?

Accidentally mixing gasoline and diesel is a common mistake one might think of, especially in a gas station where diesel and gasoline pumps are placed next to each other. 

This is what you should know if you accidentally put gas in a diesel engine:

Signs and Symptoms of Gas in Diesel Engine

You might have mixed gas and diesel if you own a vehicle and have been dealing with fuel long enough. Mixing gasoline and diesel fuel isn’t advisable; however, it sometimes happens. How much gas is put in a diesel engine might determine the extent of damage to your diesel engine.

You might probably wonder if a small amount of gas in diesel will hurt the engine. Here are some signs and symptoms of gas in a diesel engine:

No Ignition

Diesel fuels aren’t designed to ignite gasoline fuels; gasoline engines aren’t designed to ignite fuels automatically. Therefore, if you put gasoline into a diesel engine, there won’t be a spark to ignite it. If by any chance ignition takes place when both fuels are mixed up, it will be too little for smooth engine operation. 

Shock Wave Damage

Both diesel and gasoline engines have several engine moving components and parts, such as con rods, pistons, wrist pins, and crankshaft. 

If there’s an unusual detonation, the shock wave from the occurrence can damage the engine parts and cause engine knocking. 

Black Smoke

Gasoline needs a minimum of -40 degrees centigrade to ignite, while diesel needs 52 degrees centigrade. Therefore, it will be difficult for gasoline to combust in a diesel engine, leading to a huge amount of unburned fuel. 

Fuel System Damage

If gasoline gets to your diesel fuel tank, it might cause damage to your fuel pump, fuel filters, and injectors, which are the main components of the diesel fuel system. You might need to replace your entire fuel system for peak performance if these components are not working as they should. 

Inadequate Lubrication

Diesel is an “oil” that lubricates engine components, while gasoline is a solvent. Therefore, putting gasoline in a diesel engine might lead to a lack of lubrication. 

Engine Damages

If you notice that you’ve accidentally put gasoline in a diesel engine, you can salvage the engine before the damages go beyond repair. However, if you continue driving with it for long, you might damage the entire engine’s component. It’s best to avoid this because a car engine is one of the most expensive components in a vehicle. 

Is 1 Gallon of Gas in 32 Gallons of Diesel Bad?

One gallon of gasoline in 32 gallons of diesel might seem like a very little accident. However, the first thing that a little amount of gas will do is depress the diesel’s flash point, which can be dangerous because pockets of higher concentrations of gasoline can develop in a tank. Therefore, the flash point wouldn’t be consistent throughout the entire tank. 

There’s a large difference in flash point temperature between gas and diesel; therefore, it won’t take very much for gasoline to depress the flash temperature significantly. As little as 1% gasoline contamination will lower diesel’s flash point by around 180C. Therefore, the diesel fuel will prematurely ignite in the diesel engine, which might lead to engine damage.

A small amount of gas in diesel can also damage the fuel pump and mess up the diesel injectors. This happens because of a drop in lubrication because gasoline is a solvent while diesel is oil. Diesel has enough lubricity to lubricate the injectors and fuel pumps. Therefore, swapping in some gasoline often takes away this lubrication, leading to damage. 

If you continue using diesel fuel contaminated with a little gasoline, you might cause real damage to the vehicle’s computer sensors by overheating them or covering them in soot; therefore, they can’t detect anything. 

How to Test for Gas in Diesel Fuel

It’s best to shut your car down and get help immediately if you suspect that you have gas in your diesel fuel. Doing so will help you avoid further damage and prevent a fire or explosion. 

Once you seek help from a trusted professional, they will probably take a fuel sample and send it to the laboratory for a specific gravity test to determine if there’s a mixture of gasoline and diesel in your tank. 

The laboratory might also use a chemistry technique known as fractional distillation to identify diesel and gasoline cross-contamination. A specific method employed for this technique is called ASTM D86, where equipment deployed in fractional distillation is typically a round bottom flask, fractional column, thermometer, condenser, and distillation adaptors. 

Use a Diesel Fuel Contamination Kit

You can also buy a diesel fuel kit to know everything you need to know about the diesel fuel in your tank. 

The good thing about these diesel fuel contamination kits is that they are affordable, low-cost, easy to use, and can help you detect if you have a fuel problem before you get engine damage. 

If you’ve stored diesel fuel, it’s also a great idea to use diesel fuel kits every three months to ensure that your fuel is not contaminated. 

Does Gas and Diesel Mix or Separate? 

Diesel and gasoline are each a blend of hydrocarbon compounds derived from crude petroleum oil. If diesel and gasoline mix, they will remain mixed and won’t separate unless they are subjected to a distillation process. 

It’s best to understand that the two fuels will not combust when mixed in a diesel engine, and any attempt to use such a mixture as motor fuel would be disastrous. 

How to Prevent Putting Gas in a Diesel Truck

It’s very easy for drivers who drive petrol and diesel vehicles to make the mistake of putting gas in their diesel trucks. 

Filling your diesel tank with gasoline is not the end of the world, especially if you realized your mistake quickly and did not try to start the engine. However, a loss of concentration at the pump or a momentary lapse of thought can make you put gas in your diesel truck.

However, you can avoid putting gas in a diesel truck by doing the following:

Put a Sticker on the Filler Cover

One of the best ways of avoiding putting the wrong fuel in your fuel tank is to put a sticker on the filler cover to remind you what fuel is required. 

It’s also best to consciously remind yourself what fuel is required rather than fill up on autopilot. 

Get a Brightly Colored Fuel Cap

In addition to a warning sticker, a brightly colored fuel cap will help you avoid putting gas in a diesel tank.

Get a Diesel Filler Neck 

Filler-neck devices can also prevent misfuelling gas into a diesel tank. Filler-neck devices such as Diesel Fill, Diesel Key, Fuel Angel, and SoloDiesel are neck fittings and will not allow narrow petrol nozzles to open their neck restrictors. 

However, the disadvantage with the above designs is that they won’t accept a high-flow truck bowser nozzle and need to be removed if that’s the only available nozzle. 

Double-Check the Pump

Confirming your fuel cap and the pump have the same name before fueling is always best.

Stay Focused

Do not get distracted or go on autopilot while at the service station. Instead, it’s best to stay focused and take your time to double-check to avoid any mishaps at the service station. 

What to Do if You Put Some Gas in a Diesel Vehicle 

Do not panic if you accidentally put gas in a diesel vehicle tank. You can do a few things to save your vehicle from sustaining any real damage. Here are some of the things you can do to avoid damaging your vehicle:

  • First, leave the vehicle exactly where it is, and do not try to start the engine.
  • Don’t start the ignition because any attempt to turn the ignition key to the “on” position will activate the fuel pump and fuel injectors.
  • If you already started your car and started driving before realizing the error, pull over to a parking lot or the side of the road and call for a tow track. 
  • Call for a tow truck to come and tow your vehicle away from the gas station. Then, have the tow truck take your car to your local dealership or any trustworthy auto mechanic.
  • The mechanic will probably drain the fuel tank and flush out the fuel system. If you do not turn on your car, the gasoline will not contaminate any internal components. 
  • Do not drive your car until your mechanic drains the fuel completely. 

How Much Does it Cost to Repair Gas in Diesel Engine Damage? 

Gas in diesel repair cost is relatively affordable because draining diesel from a gas tank is a pretty straightforward job that will likely cost several hundred dollars. 

However, if further damage was caused by running the vehicle with diesel fuel, the cost could extend into a few thousand dollars. 

Check this too: Signs That Your Diesel High-Pressure Fuel Pump Is Failing

Remember not to start your vehicle if you’ve accidentally filled it up with gas instead of fuel. It’s best to have your car towed to a mechanic to drain the fuel because if you start your car and run it using gas, it can cause more serious damage and a costly repair. 

Petrol contaminating diesel is common, especially if you’re not alert at the service station. Do not panic if you accidentally put gasoline in a diesel tank. You can save your car’s engine by not starting your car and calling a tow truck to take your vehicle to a mechanic to drain the fuel.