What Should You Never Mix With Diesel? (7 Common Chemicals)

Mixing certain substances with diesel fuel can be dangerous or detrimental to the performance of a diesel engine. Here are some substances that should never be mixed with diesel and the reasons why:

Gasoline: Mixing gasoline with diesel, even in small amounts (e.g., 5% gasoline to 95% diesel), can cause significant problems. Gasoline has a lower flash point than diesel, making the mixture more volatile and prone to ignition. This can lead to engine knocking, reduced lubrication, and potential engine damage.
Water: Water contamination in diesel fuel, even in small quantities (e.g., 0.5% water by volume), can lead to microbial growth, rust, and corrosion. Water in diesel can also cause the fuel to separate, leading to reduced combustion efficiency and potential damage to fuel injectors and other components.
Ethanol or Methanol: These alcohols should not be mixed with diesel. Even a small percentage (e.g., 2-3% by volume) can lead to phase separation, where the alcohol and diesel do not mix evenly. This separation can cause inconsistent burning, damage to the fuel system, and reduced lubrication.
Used Motor Oil: Some people might consider adding used motor oil to diesel as a recycling method. However, used motor oil can contain contaminants and additives that are harmful to diesel engines. These contaminants can clog fuel filters and injectors, leading to reduced engine performance and increased emissions.
Kerosene: While kerosene can be mixed with diesel in certain situations, like to prevent gelling in cold weather, the mixture must be done carefully and in specific ratios (e.g., no more than 30% kerosene to 70% diesel). Improper mixing can lead to reduced lubrication, damage to fuel pumps and injectors, and decreased engine performance.
Biodiesel in High Concentrations: Biodiesel is often mixed with traditional diesel in varying proportions. However, using high concentrations of biodiesel (above B20, which is 20% biodiesel, 80% diesel) without proper engine modifications can lead to engine damage due to its different chemical properties, such as higher viscosity and potential for increased microbial growth.
Chemical Additives without Approval: Adding unapproved chemical additives or homemade concoctions can be harmful. These substances might interact negatively with diesel, leading to reduced performance, increased emissions, or even engine damage.

It’s essential to follow the manufacturer’s guidelines for fuel use and to avoid experimenting with diesel fuel mixtures, as improper combinations can lead to serious engine problems, increased maintenance costs, and safety hazards.

10 Chemicals That Can Be Mixed With Diesel

Mixing other substances with diesel fuel requires caution, as diesel engines are designed for specific fuel properties. However, there are certain additives and substances that can be mixed with diesel under the right conditions to improve its performance, efficiency, or to adapt to environmental conditions. Here’s a technical overview:

Cetane Improvers: These additives increase the cetane number of diesel fuel, improving combustion efficiency. A common cetane improver, 2-Ethylhexyl nitrate, can be added at concentrations typically around 0.1% by volume, potentially increasing the cetane number by 3 to 5 points. This leads to better cold starting, reduced engine noise, and lower emissions.
Lubricity Additives: Modern ultra-low sulfur diesel (ULSD) can have reduced lubrication properties. Adding lubricity improvers, such as fatty acid methyl esters (FAME), at concentrations around 200 to 500 ppm (parts per million) can protect fuel system components from wear, especially in high-pressure systems.
Cold Flow Improvers: To prevent wax crystal formation in cold weather, cold flow improvers are used. These additives, such as ethylene-vinyl acetate copolymers, are typically added at concentrations of 0.05% to 0.2% by volume. They modify the size and shape of wax crystals, preventing fuel filter plugging at low temperatures.
Antioxidants: Diesel, especially biodiesel blends, can oxidize over time. Antioxidants like Butylated hydroxytoluene (BHT) are added at levels of 100 to 200 ppm to prevent oxidation, which can lead to gum formation and fuel degradation.
Corrosion Inhibitors: To protect the fuel system from corrosion, especially in the presence of water, corrosion inhibitors are added. Typical concentrations are in the range of 50 to 100 ppm. They form a protective layer on metal surfaces, preventing rust and corrosion.
Biocides: Water contamination in diesel can lead to microbial growth. Biocides, such as isothiazolones, are added at concentrations of about 100 to 1000 ppm to kill microbes and prevent their growth in fuel storage systems.
Detergents: To keep injectors and other fuel system components clean, detergents like alkylamines or polyetheramines are added. They are usually present in concentrations of 50 to 300 ppm, helping to prevent deposit formation and maintaining engine performance.
Stabilizers: For long-term storage of diesel, stabilizers can be added to prevent fuel degradation. These additives, typically used at concentrations of 100 to 200 ppm, are especially important for biodiesel blends, which can degrade more rapidly than conventional diesel.
Defoamers: To reduce foaming during fueling, defoamers like silicone-based compounds are added in small amounts, typically around 10 ppm. They reduce the surface tension of the fuel, preventing excessive foam formation.
Biodiesel: Biodiesel can be mixed with traditional diesel in varying proportions, commonly seen as B5 (5% biodiesel, 95% diesel) or B20 (20% biodiesel, 80% diesel). However, it’s important to adhere to engine manufacturer’s specifications, as higher concentrations of biodiesel can affect engine performance and warranty.

While there are several substances that can be safely mixed with diesel to enhance its properties, it’s crucial to use these additives in the correct concentrations and to adhere to engine and fuel system specifications. Overuse or incorrect application can lead to engine damage, reduced performance, or other complications. Therefore, it’s always recommended to follow the guidelines provided by the fuel supplier and engine manufacturer.

Uncommon Chemical Interactions

Discussion of Specific Chemical Additives

Octane Boosters: Octane boosters, typically used in gasoline, are sometimes mistakenly added to diesel to enhance performance. However, diesel engines operate on cetane numbers rather than octane ratings. The introduction of octane boosters can alter the cetane number of diesel fuel, leading to poor ignition quality. For instance, adding 2% by volume of a typical octane booster can decrease the cetane number by up to 5 points, adversely affecting engine start-up and smoothness of operation.
Ethanol or Methanol-Based Additives: These are sometimes added under the misconception that they can clean injectors or improve combustion. However, diesel engines are not designed to handle the chemical properties of alcohols. Adding as little as 1% of ethanol or methanol by volume can cause phase separation, where the alcohol does not mix evenly with the diesel, leading to inconsistent fuel composition, potential corrosion, and reduced lubrication properties.

Explanation of Unexpected Reactions

The addition of these substances can lead to an increase in the formation of gums and varnishes within the fuel system. For example, the interaction of ethanol with certain diesel fuel components can produce sticky residues that clog fuel filters and injectors.
Alteration in fuel viscosity: Adding certain additives can change the viscosity of diesel fuel. For example, adding 0.5% of certain industrial solvents can increase fuel viscosity by 10-15%, impacting the fuel injection system’s efficiency and potentially leading to incomplete combustion.

Industrial Solvents

Examination of Industrial Solvents

Aromatic Solvents: Solvents like toluene or xylene are sometimes present in industrial environments and can inadvertently contaminate diesel fuel. Even a small contamination level, such as 1% of toluene by volume, can reduce the cetane number of diesel, impacting ignition quality. Additionally, these solvents can degrade rubber components in the fuel system, leading to leaks or failures.
Chlorinated Solvents: Chlorinated solvents, if mixed with diesel, even in small quantities like 0.2% by volume, can lead to the formation of hydrochloric acid during combustion. This acid can corrode engine components and exhaust systems, leading to significant damage over time.

Analysis of the Impact on Fuel Quality and Combustion Efficiency

Reduced Combustion Efficiency: The presence of these solvents can lower the energy content of diesel fuel. For instance, a 1% volume addition of certain aromatic solvents can decrease the fuel’s calorific value by approximately 0.5%, leading to reduced engine power output.
Emission Problems: Solvent contamination can lead to incomplete combustion, increasing emissions of unburned hydrocarbons, carbon monoxide, and particulate matter. This not only affects engine performance but also contributes to environmental pollution.
Fuel System Damage: Some solvents can react with components in the fuel system, leading to the breakdown of hoses, seals, and gaskets. Over time, this degradation can cause fuel leaks and reduced system integrity.

The introduction of uncommon chemical additives and industrial solvents into diesel fuel can lead to a range of technical issues, from altered combustion characteristics to physical damage within the fuel system. It’s crucial for diesel fuel users to be aware of these risks and ensure fuel purity to maintain engine health and performance.

Read related article: What is the Difference Between Red and Green Diesel?

Environmental Contaminants

Less Obvious Sources of Water Contamination

Condensation: Condensation in diesel fuel tanks is a common but often overlooked source of water contamination. Temperature fluctuations can cause moisture from the air to condense inside the tank. For instance, a 10,000-liter tank experiencing a temperature change from 5°C to 20°C can accumulate up to 100 milliliters of water per day due to condensation.
Environmental Humidity: High environmental humidity can also contribute to water contamination in diesel. In regions with relative humidity levels above 80%, the moisture absorption rate of diesel can increase significantly. For example, diesel stored in an open container in such an environment can absorb up to 50 ppm (parts per million) of water from the air in 24 hours.

Effects of Water Contamination on Diesel Engines

Microbial Growth: Water in diesel can lead to microbial growth, such as bacteria and fungi. These microbes can produce biofilms and slimes that clog fuel filters and injectors. For instance, a water content as low as 200 ppm in diesel can support microbial growth, leading to fuel system blockages.
Corrosion: Water in diesel can cause corrosion of metal parts in the fuel system. Even minimal water content (around 100 ppm) can initiate corrosion processes, especially in high-pressure common-rail systems.
Fuel Injection Problems: Water reduces the lubricity of diesel fuel, causing increased wear on fuel injectors and pumps. A study showed that water levels above 500 ppm in diesel can increase injector wear by up to 20%.

Airborne Particulates

Impact of Airborne Particulates on Diesel

Dust and Dirt: Particulates like dust and dirt, common in industrial or construction areas, can enter diesel storage tanks. These particulates, even in small quantities (e.g., 5 mg/L), can cause abrasion and wear in the fuel system, particularly in high-precision components like injectors.
Metallic Particles: Metallic particles, often resulting from industrial activities or wear of engine components, can contaminate diesel. Concentrations as low as 1-2 mg/L of metallic particles can accelerate wear and tear in fuel pumps and injectors.

Specific Examples of Particulates and Their Sources

Construction Sites: Diesel stored near construction sites can accumulate significant amounts of silica dust. Silica particles, even at concentrations of 10-15 mg/L, can increase fuel system wear and reduce the efficiency of fuel filters.
Industrial Emissions: Soot and ash from industrial emissions can mix with diesel, especially in urban areas. These particulates can increase the viscosity of diesel and affect combustion, leading to higher emissions and reduced engine performance.

Water contamination and airborne particulates significantly impact diesel fuel quality and engine performance. Understanding these environmental factors and implementing measures to mitigate their effects is crucial for maintaining the efficiency and longevity of diesel engines.

Read related article: How to Increase Diesel Fuel Cetane? (5 Effective Methods)

Unintended Mixtures During Storage and Transport

Cross-Contamination in Storage Facilities

Analysis of Diesel Contamination During Storage

Contamination from Previous Contents: Storage tanks previously used for other substances can contaminate diesel. For instance, residual gasoline in a tank, even at levels as low as 0.1% by volume, can significantly alter the flash point of diesel, posing a safety risk.
Mixing with Residues and Sediments: Over time, storage tanks accumulate sediments and residues that can mix with fresh diesel. A sediment concentration of just 100 mg/L can cause fuel filter clogging and fuel system wear.
Chemical Reactions with Storage Materials: Interaction between diesel and certain storage materials, like certain types of rubber or plastic, can lead to contamination. For example, certain plastics can leach phthalates into diesel at concentrations up to 10 ppm, affecting fuel quality.

Preventative Measures and Best Practices for Storage

Regular Tank Cleaning: Implement a schedule for regular cleaning of storage tanks to remove sediments and residues. Tanks should be cleaned at least once every two years to prevent significant sediment buildup.
Use of Appropriate Materials: Ensure that all materials used in tank construction and maintenance are compatible with diesel. For example, use storage tank liners made of materials that do not react with diesel or leach contaminants.
Proper Tank Sealing: Seal tanks effectively to prevent ingress of water, dust, and other contaminants. This includes maintaining gaskets and seals in good condition to prevent exposure to environmental contaminants.

Transport-Related Risks

Examination of Transport-Related Risks

Contamination during Loading and Unloading: Contamination can occur during the loading and unloading process. For example, if transfer hoses are not properly cleaned, residual substances from previous loads, even in small amounts like 0.05% by volume, can contaminate the diesel.
Contamination from Transport Vehicle: The interior surfaces of transport tanks can introduce contaminants. Rust particles from corroded tank walls, for instance, can enter diesel at concentrations of 5-10 mg/L, impacting fuel quality.
Temperature-Induced Issues: During transport, temperature changes can lead to condensation, increasing the risk of water contamination in diesel. A temperature change of 15°C can result in condensation that increases water content in the diesel by up to 200 ppm.

Guidelines for Ensuring Purity during Transport

Regular Tanker Inspection and Maintenance: Conduct regular inspections and maintenance of transport tankers to prevent rust and corrosion. Ensure that tankers are cleaned thoroughly between deliveries.
Temperature Control: Implement temperature control measures, especially in regions with large temperature fluctuations, to minimize condensation risk.
Strict Loading/Unloading Protocols: Establish and enforce strict protocols for the loading and unloading of diesel, including the use of dedicated hoses and fittings for diesel only. This practice minimizes the risk of cross-contamination from other substances.

Managing the risks of unintended mixtures during the storage and transport of diesel requires diligent adherence to best practices and protocols. Regular maintenance, appropriate materials selection, and strict handling procedures are key to ensuring diesel fuel integrity and preventing contamination.

Biodiesel and Alternative Diesel Formulations

High Concentrations of Biodiesel

Risks of Using High Concentrations of Biodiesel in Standard Diesel Engines

Material Compatibility: Biodiesel at high concentrations (above B20, i.e., 20% biodiesel, 80% petroleum diesel) can cause compatibility issues with certain engine materials. For example, B100 (100% biodiesel) can degrade natural rubber seals and hoses at a rate up to 10% faster than standard diesel, leading to leaks and part failures.
Engine Lubrication: While biodiesel has good lubricating properties, high concentrations can alter the lubrication balance in engines designed for standard diesel. For instance, B100 can increase the oil dilution rate in engines by up to 2-3%, affecting the oil’s viscosity and its ability to protect engine parts.
Fuel System Clogging: Biodiesel can act as a solvent, loosening deposits in the fuel system. In high concentrations, this can lead to increased amounts of debris (up to 50 mg/L) clogging fuel filters and injectors, especially during the initial switch from diesel to biodiesel.
Cold Weather Performance: Biodiesel has a higher cloud point than standard diesel. Using B100 can lead to fuel gelling at temperatures as high as 0°C, compared to -15°C for regular diesel, potentially causing cold start issues and fuel flow problems.

Impact on Engine Parts and Fuel Efficiency

Injector Fouling: High concentrations of biodiesel can cause injector fouling due to the formation of soap-like residues. B100, for instance, can increase injector coking up to 20% more than standard diesel, affecting engine performance and emissions.
Reduced Fuel Efficiency: Biodiesel has a lower energy content than standard diesel (about 8-10% lower for B100). This means that engines running on high biodiesel concentrations will experience a decrease in fuel efficiency, potentially by up to 10% for B100.

Experimental Diesel Blends

Discussion on Experimental or Alternative Diesel Blends

Hydrogenated Vegetable Oils (HVO): HVO is an alternative diesel fuel made from vegetable oils or animal fats. While it is more stable than traditional biodiesel, using it in high concentrations without engine adjustments can still pose risks such as altered combustion characteristics and increased NOx emissions.
Dimethyl Ether (DME): DME is a clean-burning diesel alternative with high cetane value but requires significant modifications to fuel storage and engine systems due to its gaseous state at room temperature.

Potential Risks of Experimental Blends

Combustion Characteristics Alteration: Alternative diesel blends can alter the combustion process in engines designed for standard diesel. For example, DME’s high cetane value can lead to premature combustion, potentially causing engine knocking and damage.
Storage and Handling Issues: Some experimental blends require different handling and storage solutions. For instance, DME requires pressurized storage systems, increasing the complexity and potential safety risks.

Importance of Manufacturer-Approved Fuel Types

Using manufacturer-approved fuel types ensures engine longevity and reliability. These fuels are tested to meet specific engine requirements, ensuring optimal performance and minimizing the risk of damage.
Warranty Considerations: Using unapproved fuel types can void engine warranties, leaving users with no recourse in case of damage related to fuel use.
Regulatory Compliance: Manufacturer-approved fuels are often required to meet regulatory standards for emissions and safety. Using alternative fuels can lead to non-compliance with these regulations.

While exploring biodiesel and alternative diesel formulations presents opportunities for cleaner and more sustainable fuel options, it’s crucial to understand their impact on engine performance, fuel efficiency, and overall safety. Adhering to manufacturer guidelines and regulations is essential to ensure engine health and compliance with environmental standards.

Conclusion

The exploration of substances that should never be mixed with diesel highlights the delicate balance required to maintain diesel fuel integrity and engine performance. From the risks posed by uncommon chemical additives and industrial solvents to the challenges presented by environmental contaminants like water and airborne particulates, each factor underscores the importance of diligent fuel management.

Additionally, the complexities surrounding high concentrations of biodiesel and experimental diesel blends demonstrate the need for adherence to manufacturer specifications and careful consideration of fuel choices. Ultimately, understanding and avoiding these potentially harmful mixtures is crucial for ensuring the safe and efficient operation of diesel engines, minimizing maintenance issues, and upholding environmental standards.

This awareness is key to optimizing the longevity and reliability of diesel-powered systems, making it essential knowledge for all who rely on diesel fuel in their operations.