What Happens if You Put Gas in a Diesel Engine?

Long-Term Effects of Gasoline Contamination in Diesel Engines

Decreased Fuel Efficiency

One of the lasting impacts of gasoline in a diesel engine is a significant drop in fuel efficiency. Diesel engines are designed to run specifically on diesel, which has a different energy density than gasoline. Using gasoline can cause incomplete combustion, meaning more fuel is burned without generating sufficient power. Over time, this can lead to lower miles per gallon (MPG), reducing the vehicle’s overall performance and making it more costly to operate.

Potential Engine Replacement

In severe cases where gasoline has circulated extensively through a diesel system, parts like the fuel injectors, fuel pump, and even the engine block can suffer extensive damage. Replacing these parts can be pricey, and when combined with labor costs, the total bill may approach the cost of replacing the entire engine. For older vehicles or those with high mileage, engine replacement may be the only viable option. This is why timely intervention is crucial after misfuelling.

Resale Value Impact

Putting gasoline in a diesel engine not only affects performance but can also lower the vehicle’s resale value. Potential buyers often view engine damage history negatively, especially if the repairs were extensive. Moreover, misfuelling incidents can raise questions about other potential maintenance lapses, which could deter buyers or reduce the amount they’re willing to pay.

Why Gasoline and Diesel Are Not Interchangeable

Chemical and Physical Differences

Diesel fuel and gasoline have fundamentally different compositions and burning characteristics. Diesel is heavier and has a higher energy density, while gasoline is lighter and evaporates more readily. Diesel also has lubricating properties that gasoline lacks, making it essential for the diesel engine’s longevity and proper functioning. The combustion properties of each fuel are tailored for specific engine types, so swapping one for the other disrupts the entire engine’s performance and durability.

How Diesel Engines Depend on Diesel Fuel’s Properties

Diesel engines are designed to rely on diesel’s higher cetane number (a measure of the fuel’s combustion quality). This allows diesel to ignite under high pressure without the need for spark plugs, unlike gasoline engines. When gasoline is introduced, it lacks the cetane level needed, causing incomplete combustion, loss of power, and potential damage to engine components.

Preventative Measures to Avoid Misfuelling

Use Fuel Nozzle Compatibility Devices

Several products on the market can help prevent misfuelling by making it impossible to insert a gasoline nozzle into a diesel tank. These devices, often called misfuelling prevention devices or filler neck adapters, provide a safeguard, especially useful for fleet vehicles or families with multiple cars.

Pay Attention to Fuel Labels

An easy and cost-free prevention method is paying close attention to fuel labels at the pump. Diesel fuel pumps are typically labeled with green handles or stickers to differentiate them from gasoline. Additionally, reading labels can be a simple but effective way to ensure you’re filling up correctly.

Install Fuel Cap Labels

Diesel car owners can benefit from placing a “Diesel Only” sticker on the fuel cap. This small visual reminder can prevent accidents, especially if others sometimes drive the vehicle or if it’s part of a shared fleet.

Alternative Fuels and Diesel Engine Compatibility

Biodiesel and Other Diesel-Compatible Options

While gasoline is off-limits, diesel engines can sometimes accommodate certain alternative fuels, like biodiesel blends (B20, B100). Biodiesel is derived from vegetable oils or animal fats and is a viable, renewable substitute for traditional diesel in some engines. However, it’s important to confirm compatibility with the manufacturer, as not all diesel engines are designed for high biodiesel blends.

Risks of Other Non-Diesel Fuels

It’s not just gasoline that’s incompatible with diesel engines; kerosene, ethanol, and other fuels can also cause harm. These fuels lack the energy density and lubricating qualities necessary for diesel engines. Using any non-diesel fuel can lead to similar issues of poor combustion, excessive wear, and costly repairs.

Common Myths about Fuel in Diesel Engines

“A Little Gasoline Won’t Hurt”

One widespread myth is that a small amount of gasoline won’t harm a diesel engine. However, even minor contamination can cause significant issues. Gasoline disrupts the lubrication diesel provides, leading to friction in essential components. So even a few gallons of gasoline mixed with diesel can result in major repairs if it circulates through the system.

Using Gasoline to “Clean” Diesel Engines

Some drivers mistakenly believe that gasoline can be used to “clean” a diesel engine by flushing out carbon deposits. This myth is not only incorrect but also harmful. Gasoline is a solvent, not a cleaner for diesel engines, and its use can lead to critical damage to parts and components, resulting in expensive repairs.

What to Do if the Engine Was Already Started

Turn Off the Engine Immediately

If gasoline accidentally enters a diesel tank and the engine has already been started, the best course of action is to turn it off immediately. Running the engine only allows gasoline to circulate, increasing the chances of damage. By stopping the engine, you minimize the fuel’s spread, allowing a mechanic to better clean out the contaminated fuel.

Steps for Fast Recovery

In the event that gasoline has circulated through the system, quick action can still save the engine from irreversible damage. Calling a mechanic to drain the fuel tank and flush the system as soon as possible limits long-term issues. It’s crucial to resist any attempts at self-repair, as diesel engines require professional handling for this type of contamination.

Emergency Kit for Diesel Car Owners

Recommended Tools and Supplies

Diesel car owners can benefit from keeping an emergency kit on hand that includes essentials like a fuel siphon pump, a funnel, and a bottle of diesel fuel additive. While these tools can’t reverse a misfuelling, they may help in a pinch or allow you to drain other contaminants from your tank.

Importance of Being Prepared

An emergency kit can be a lifesaver if misfuelling or another fuel-related problem occurs in a remote area. These tools, combined with knowledge of your vehicle’s requirements, can make dealing with fuel issues much less stressful and help avoid costly repairs in certain situations.

The Role of Diesel in Engine Durability and Power

Diesel’s Lubrication Benefits

Diesel fuel naturally provides lubrication to essential engine components, reducing friction and promoting durability. This lubrication is crucial because diesel engines are subject to high stress and operate under extreme conditions. Gasoline, on the other hand, lacks this quality, making diesel engines more vulnerable to damage when contaminated.

Diesel’s Power Generation

Diesel fuel’s high energy density makes it highly efficient, allowing diesel engines to generate more torque and power than gasoline engines. This is why diesel is often preferred for heavy-duty vehicles like trucks and construction equipment. Misfuelling with gasoline disrupts this power generation process, weakening performance and damaging internal parts.

Conclusion

Putting gasoline in a diesel engine is a mistake that can lead to significant and costly consequences. Diesel engines are engineered specifically to work with diesel fuel, so introducing gasoline can cause anything from minor performance issues to extensive engine damage. From high repair costs to potential engine replacement, the risks are substantial. The best approach is prevention—staying alert at the pump, using fuel labels, and considering a misfuelling prevention device can save you a lot of hassle and expense. Remember, quick action and professional help are essential if misfuelling ever happens to you.

FAQs

1. What happens if I accidentally add a small amount of gasoline to a diesel tank? Even a small amount of gasoline can disrupt the lubrication properties diesel provides. If this happens, it’s best to avoid starting the engine and seek professional help to drain and clean the tank.

2. Is it safe to drive a diesel car after misfuelling if I don’t feel any symptoms? Driving after misfuelling without addressing it can lead to gradual damage that may not show up immediately. It’s best to have the fuel system checked and cleaned to prevent future issues.

3. How can I tell if my diesel engine has been affected by gasoline? Common symptoms include difficulty starting, rough idling, unusual noises, excessive smoke, and dashboard warning lights. If any of these signs appear after misfuelling, get your vehicle checked by a mechanic.

4. Can adding additives fix gasoline contamination in a diesel engine? No, fuel additives won’t reverse the effects of gasoline contamination. Diesel engines require a full draining and cleaning of the fuel system to avoid damage.

5. What should I do if I misfuel my diesel vehicle late at night? If this happens at night, avoid starting the engine and call a roadside assistance service that offers fuel system draining. Many services operate 24/7, so help should be available when needed.