Diesel vs. Biodiesel vs. Vegetable Oil: Key Insights and Test Results

On February 25, 2026  By newsroom   Topic: Automotive


1. Overview of Fuels

  • Diesel: The baseline fuel, widely available and suitable for unmodified diesel engines.
  • Biodiesel (B5, B20, B100): Derived from vegetable or animal fats, blended with petroleum diesel.
  • B5: 5% biodiesel, 95% petroleum diesel.
  • B20: 20% biodiesel, 80% petroleum diesel.
  • B100: Pure biodiesel, renewable but expensive and less convenient.
  • Vegetable Oil: Used fryer oil, often free from restaurants but requires filtering and engine modifications.

2. Performance

| Fuel | Fuel Economy (MPG) | Acceleration (0-60 mph) | Cost |
|-------------------|------------------------|-----------------------------|-----------------------------|
| Diesel | 45 | 15 seconds | Standard price |
| B5 (5%) | 49 (best) | 14.2 seconds (best) | Similar to diesel |
| B100 (100%) | 44 | 15 seconds | $0.85 more per gallon |
| Vegetable Oil| 42 | 15 seconds | Low/free but labor-intensive|


3. Emissions

| Emission Type | Diesel | B5 | B100 | Vegetable Oil |
|---------------------|------------|--------|----------|-------------------|
| Hydrocarbons | 3 ppm | 3 ppm | 9 ppm | 14 ppm |
| NOx (Nitrogen) | Moderate | Moderate| High | Lowest |
| Particulates | Moderate | Moderate| Lowest | Lowest |
| CO2 (Carbon) | ~19 lbs/gal for all fuels, offset claims by biofuels disputed. |

Key Takeaways:
- Biodiesel fuels generally had cleaner emissions than diesel.
- Cooking oil had the lowest NOx and particulate emissions but higher hydrocarbons.


4. Convenience and Practicality

Diesel

  • No modifications required.
  • Standard fuel stations; widely available.

B5 (5% Biodiesel)

  • No engine modifications needed.
  • Best balance of performance, fuel economy, and emissions.
  • Convenient to use at standard pumps.

B100 (100% Biodiesel)

  • Renewable but costly.
  • No significant fuel economy or performance advantage over diesel.
  • Limited manufacturer warranty coverage beyond B20.

Vegetable Oil

  • Renewable and free/low cost but highly labor-intensive:
  • Requires finding, filtering, and storing oil.
  • Engine modifications needed (e.g., auxiliary tank).
  • Additional setup steps before and after driving:
  • Start with diesel and purge system after use.
  • Can result in diesel mixing with cooking oil if not managed correctly.

5. Modifications for Testing

  • Engine Conversion: A $1,550 kit from Greasecar Vegetable Fuel Systems was installed, including:
  • A 13-gallon auxiliary tank for vegetable oil.
  • Additional fuel lines, inline filters, and switches.
  • Installation Time: 10 hours by a certified mechanic.
  • Extra Testing Tanks:
  • Two additional 5-gallon tanks installed for B100 and B5 fuels.
  • Labor for Vegetable Oil: Collecting, filtering, and storing oil required significant effort.

6. Experts' Recommendations

  • Best Overall: B5 Biodiesel
  • Offers the best balance of convenience, fuel economy, and environmental benefits.
  • Widely supported by automakers for use in diesel engines.

  • Renewable but Challenging: Vegetable Oil

  • Suitable for enthusiasts willing to invest time and effort.
  • Requires engine modifications and ongoing maintenance.

  • Not Economical: B100 Biodiesel

  • While renewable, it has no financial advantage and limited warranty coverage.

  • Reliable Choice: Diesel

  • Best for users prioritizing availability and simplicity.

7. Conclusion

While diesel remains a practical choice for performance and availability, B5 biodiesel is the most accessible eco-friendly alternative. Vegetable oil is a niche option for dedicated hobbyists, while B100 biodiesel, though renewable, is costly and less convenient.

For a sustainable and hassle-free transition, stick with B5 or B20 blends.


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