Can You Use Diesel Additives in Biodiesel?

Can You Use Diesel Additives in Biodiesel?

Using diesel additives in biodiesel is a common practice to improve various properties of the fuel. However, the effectiveness and appropriateness of additives depend on the specific type of biodiesel and the desired outcomes. Here are some technical aspects and measurements to consider:

  1. Cetane Improvers: The fuel typically has a higher cetane number than petrodiesel. Adding cetane improvers may not be necessary unless the fuel is of lower quality. The cetane number of diesel fuel is typically between 40 and 55, while biodiesel can range from 47 to 65. Adding more cetane improvers to biodiesel with already high cetane numbers is generally not beneficial.
  2. Cold Flow Improvers (CFIs): The fuel can gel at higher temperatures compared to regular diesel. CFIs are added to reduce the pour point and cold filter plugging point (CFPP) of this fuel. The effectiveness of CFIs depends on the composition of this fuel. For example, fuels that are made from animal fats requires more effective CFIs due to its higher gel point. The typical pour point for biodiesel is around -3°C to 12°C, and CFIs can lower this by several degrees.
  3. Oxidation Stabilizers: The fuel is more prone to oxidation than petrodiesel, leading to the formation of gums and sediments. Antioxidants like BHT (Butylated Hydroxytoluene), TBHQ (Tertiary Butylhydroquinone), and propyl gallate are added to extend the storage life. The ASTM D6751 standard for biodiesel sets a minimum oxidation stability requirement of 3 hours (measured by the Rancimat method), and antioxidants can improve this significantly.
  4. Corrosion Inhibitors: This fuel can be more corrosive than diesel, especially to certain metals like copper. Adding corrosion inhibitors can protect engine components and storage tanks. The corrosion levels are measured by the NACE TM0172 method, where a rating of A (no corrosion) to D (severe corrosion) is given.
  5. Detergents and Dispersants: These are used to keep the fuel system clean and prevent the formation of deposits. The concentration of detergents and dispersants in biodiesel varies based on the feedstock and production process.
  6. Biocide Additives: This fuel is more susceptible to microbial growth due to its ester content. Biocides like Kathon or Biobor JF are used to control microbial growth, which is crucial for biodiesel stored for long periods.
  7. Compatibility with Petrodiesel: Since biodiesel is often blended with petrodiesel, additives must be compatible with those in petrodiesel. Biodiesel blends are denoted as BXX, where XX is the percentage of biodiesel in the blend. Common blends include B5 (5% biodiesel, 95% diesel) and B20 (20% biodiesel, 80% diesel).
  8. Alcohol Content: Biodiesel production involves transesterification, where alcohol is a key reactant. Residual alcohols in the fuel can affect fuel properties. The ASTM standard sets a maximum limit of 0.2% for methanol content.
  9. Viscosity: The viscosity of biodiesel is typically higher than that of petrodiesel. The ASTM D6751 standard specifies a viscosity range of 1.9 to 6.0 mm²/s at 40°C for this fuel. Additives can be used to modify viscosity, but it’s less common as its viscosity is usually within a suitable range for most engines.
  10. Density: The density of this fuel affects fuel injection and atomization. The typical density range is 0.86 to 0.90 kg/L at 15°C, which is slightly higher than that of petrodiesel.

When using additives in biodiesel, it is crucial to ensure that they are compatible with the biodiesel blend and meet the relevant fuel standards like ASTM D6751 or EN 14214. Overuse or incorrect use of these conditioners can lead to engine damage or reduced fuel efficiency. Always consult with fuel experts or engine manufacturers when considering its use for biodiesel.

Read related article: Can Using Diesel Additives Void Vehicle’s Warranty?

What Additives Are Used in Biodiesel?

In biodiesel, various additives are used to enhance its performance, stability, and compatibility with engines and fuel systems. The choice depends on the specific properties of the biodiesel, its intended use, and the local climate. Here are some of the common additives used in biodiesel:

  1. Cetane Improvers: These additives increase the cetane number of the fuel, leading to improved ignition quality. Higher cetane numbers result in better cold starting, smoother running, and reduced engine noise. However, since biodiesel naturally has a high cetane number, the use of these improvers might be less compared to regular diesel.
  2. Cold Flow Improvers (CFIs): It can gel or solidify in cold temperatures, leading to fuel line blockages. CFIs are added to lower the cloud point (the temperature at which wax crystals begin to form) and the pour point (the lowest temperature at which the fuel remains fluid). This is particularly important in colder climates.
  3. Oxidation Stabilizers: It is prone to oxidation, which can cause the formation of sediments and gum. Antioxidants such as Butylated Hydroxytoluene (BHT), Tertiary Butylhydroquinone (TBHQ), or propyl gallate are added to prevent this. These stabilizers extend the storage life of biodiesel and maintain fuel quality.
  4. Corrosion Inhibitors: These additives protect metal parts of the fuel system and engine from corrosion, which can be caused by some components of the fuel. They are especially important for biodiesel blends and in environments with high humidity.
  5. Detergents and Dispersants: To keep fuel injectors and other engine parts clean, detergents and dispersants are added. They help in preventing deposit formation and maintaining engine efficiency.
  6. Biocides: Microbial growth can be an issue in biodiesel due to its organic nature. Biocides are added to prevent the growth of bacteria and fungi, especially in storage tanks.
  7. Lubricity Additives: Biodiesel has good natural lubricity, often better than petrodiesel. However, in certain blends or formulations, additional lubricity additives may be used to ensure sufficient lubrication of engine components.
  8. Alcohol Scavengers: These additives are used to bind residual alcohols that can be present in the fuel due to its production process. They help in reducing the risk of corrosion and other issues caused by these alcohols.
  9. Acidity Neutralizers: To maintain the pH and avoid acidic conditions that can lead to corrosion, acidity neutralizers are sometimes added.
  10. Demulsifiers: Water contamination can lead to microbial growth and other issues. Demulsifiers are used to separate water from the biodiesel, ensuring fuel quality and preventing engine problems.

It’s important to note that the use and concentration of these additives should be carefully managed. Overuse or inappropriate use can lead to engine damage, reduced efficiency, or non-compliance with fuel standards such as ASTM D6751 in the U.S. or EN 14214 in Europe. Additionally, when biodiesel is used in blends with petrodiesel, the compatibility of additives with both types of fuel must be considered.

Compatibility of Diesel Additives with Biodiesel

A. Chemical Compatibility of Additives with Biodiesel

  • Many diesel additives mix well with biodiesel.
  • The fuel is made from vegetable oils or animal fats, often blends seamlessly with common diesel additives.
  • For example, cetane improvers that are used in regular diesel can be compatible with biodiesel. However, since it naturally has a high cetane number, usually between 47 and 65, compared to regular diesel’s 40 to 55, the need for cetane improvers is less.

B. The Effect of Additives on Biodiesel Properties and Performance

  • Cold flow improvers are vital, especially in cold climates. It can gel at temperatures between -3°C to 12°C, so additives that lower the pour point are crucial.
  • Antioxidants, like BHT or TBHQ, are added to extend the fuel’s shelf life, which is typically limited due to its proneness to oxidation. The ASTM standard demands a minimum of 3 hours of oxidation stability.
  • Lubricity conditioner, although less often needed, can be used to enhance engine performance. The fuel’s natural lubricity is already high, often surpassing that of regular diesel.

C. Potential Risks and Benefits of Using Certain Additives in Biodiesel

  • Benefits include improved cold flow, oxidation stability, and enhanced lubricity, which contribute to better engine performance and longevity.
  • Risks involve using inappropriate concentrations or incompatible additives, leading to engine damage or reduced fuel efficiency.
  • For instance, overuse of cetane improvers, which already have a high cetane number, might lead to unnecessary expense without tangible benefits.
  • It’s crucial to use additives in accordance with the fuel’s composition and characteristics to avoid issues like increased NOx emissions or reduced fuel efficiency.
  • Regular monitoring and adherence to standards like ASTM D6751 for biodiesel ensure safe and effective use of additives.

Specific Additives for Biodiesel

Specific additives for biodiesel are made to match the special needs of this type of fuel. Biodiesel is different from regular diesel because it comes from things like vegetable oil or animal fat. This means it needs its own kind of additives to work best.

These additives do a few important jobs. First, they help biodiesel stay good for longer by stopping it from going bad when it’s stored. It can easily get spoiled, so it needs these special ingredients to keep it stable and usable. Also, it can get thick and hard to pump in cold weather, so there are additives that help keep it flowing smoothly even when it’s chilly outside.

Then, there are additives that make sure the biodiesel is slippery enough to lubricate the engine well, but not too much. Plus, since biodiesel can attract microbes like bacteria and fungi, especially when stored for a long time, there are additives to stop these microbes from growing.

There are real-world examples where these additives have made a big difference. For instance, using the right antioxidants in biodiesel can make it last longer, meeting top-quality standards. And the additives that help with cold weather have made it possible to use biodiesel in places where it’s really cold, which was hard to do before.

Overall, these special agents are crucial for making biodiesel work well and be useful in different situations. Researchers are always working to make these even better, so this fuel can be more effective and environmentally friendly.

Considerations for Using Additives in Biodiesel

When using additives, there are a few important things to think about to make sure everything works well and is safe:

A. Biodiesel Blend Ratios (B5, B20, B100, etc.)

  • It is often mixed with regular diesel, and the blend is named based on how much biodiesel is in it. For example, B5 has 5% biodiesel and 95% regular diesel, B20 has 20% biodiesel, and B100 is pure biodiesel. The kind of additives you need can change depending on how much biodiesel is in the mix. A blend with a lot of biodiesel might need different additives compared to one with just a little.

B. The Impact of Climate and Engine Type on Additive Choice

  • Where you live and the weather there can affect which additives are best. In cold places, you’d want additives that stop the biodiesel from getting too thick or gelling. Also, different engines might react differently to biodiesel. Some engines are totally fine with it, while others might need specific additives to run smoothly on biodiesel.

C. Legal and Environmental Regulations to Consider

  • There are rules about what you can put in fuels, including biodiesel. These rules are there to make sure the fuel is safe and doesn’t harm the environment. It’s important to know these regulations, which can vary depending on where you are. Using the wrong additives, or using them in the wrong way, could break these rules and harm the environment, or even damage your engine.

Best Practices for Adding Additives to Biodiesel

When adding additives, it’s important to do it right to make sure your engine runs smoothly and the fuel stays in good condition. Here are some best practices to follow:

A. Guidelines for Selecting the Right Additives

  • Choose additives that match your needs. Think about what you need the additive for. Is it to keep the fuel from freezing in the cold? Or to make it last longer? Pick additives made for those specific purposes.
  • Make sure the additives are okay to use with the type of biodiesel blend you have. Some work better with certain blends.

B. Tips on Dosage and Mixing

  • Follow the instructions for how much additive to use. Using too much or too little can cause problems.
  • Mix the additives well with the biodiesel. This makes sure the additive works properly throughout the entire batch of fuel.

C. Importance of Regular Engine Maintenance When Using Additives

  • Keep an eye on your engine regularly. This helps you catch any issues early on.
  • Using additives can change how your engine runs over time. Regular check-ups can make sure everything is working as it should and that the additives aren’t causing any harm.


You can use diesel additives in biodiesel, but it’s important to choose the right ones and use them correctly. It has its own specific requirements, and the additives you select should cater to these needs, considering factors like biodiesel blend ratios, the local climate, and the type of engine.

Proper dosage and thorough mixing are crucial to ensure the additives work effectively without causing any harm. Moreover, adhering to legal and environmental regulations is essential to avoid negative impacts.

Regular engine maintenance is also key to ensuring that the biodiesel and additives continue to perform well together. By following these guidelines, you can enhance the performance and longevity of the fuel, making it a more efficient and environmentally friendly fuel option.

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