Running on Fry Oil: Vegetable Oil in Heavy Equipment Diesels

[MikePhua]

Introduction: From Kitchen to Quarry
The idea of fueling diesel engines with vegetable oil may sound unconventional, but it’s rooted in history and practicality. Rudolf Diesel’s original engine ran on peanut oil, and today, operators and tinkerers alike are revisiting this concept to reduce fuel costs and environmental impact. This article explores the feasibility, challenges, and real-world experiences of using pure vegetable oil (PVO) in heavy equipment diesels.
Key Terminology Explained

• PVO (Pure Vegetable Oil): Unprocessed or lightly filtered oil derived from plants, used as an alternative fuel.
  
• WVO (Waste Vegetable Oil): Used cooking oil that has been filtered and treated for reuse as fuel.
  
• Biodiesel: A chemically processed fuel derived from vegetable oils or animal fats, designed to mimic diesel properties.
  
• HPCR (High-Pressure Common Rail): A modern diesel injection system requiring precise fuel properties and high pressures.
  
• Inline Injection Pump: A robust fuel pump design with separate plungers for each cylinder, known for durability and tolerance to alternative fuels.
  
• Rotary/Distributor Pump: A compact fuel pump design more sensitive to fuel viscosity and contaminants.
  

Real-World Experiences: Successes and Cautions
Operators have reported varied success running heavy equipment on vegetable oil:

• A 2002 Duramax 6.6L engine ran well on filtered WVO, though experts cautioned against using PVO in HPCR systems due to their sensitivity.
  
• A 1969 John Deere 4020 operated on sunflower oil mixed with 15% diesel, emitting a scent reminiscent of French fries.
  
• A V8 Cleveland Diesel genset was successfully powered by Wesson oil heated to 140°F, demonstrating full load capacity without injector modifications.
  

These anecdotes suggest older, mechanically injected engines are more forgiving, while newer electronic systems may suffer from clogged filters or injector wear.
Best Practices for Using Vegetable Oil in Diesels

• Filter Thoroughly
  Use multi-stage filtration (e.g., 400 micron, 10 micron, 2 micron) to remove particulates and animal proteins.
  
• Heat the Oil
  Preheat to reduce viscosity, especially in cold climates. Heated tanks and fuel lines are essential for reliable starts.
  
• Use Dual Tanks
  Start and shut down on diesel; switch to vegetable oil once the engine is warm to prevent cold-start issues.
  
• Monitor Fuel System Health
  Change filters frequently and inspect injection components for wear or gumming.
  
• Avoid Dark Oils
  Oils with animal fats or proteins can cause injector fouling and are better suited for biodiesel conversion.
  

Engine Compatibility: What Works Best

• Inline Injection Pumps
  These tolerate thicker fuels and are less reliant on fuel for lubrication.
  
• Mechanical Rotary Pumps
  Can work with vegetable oil but require careful maintenance and heating.
  
• Indirect Injection Engines
  More forgiving than direct injection systems, especially when paired with inline pumps.
  
• Pre-Computerized Diesels
  Older engines without electronic controls are generally more adaptable.
  

Historical Context: Diesel’s Original Vision
Rudolf Diesel envisioned his engine running on vegetable oils to empower farmers with fuel independence. His 1900 demonstration used peanut oil, and early diesel engines were designed with fuel flexibility in mind. The shift to petroleum-based diesel was driven by industrial convenience, not technical necessity.
Modern Challenges and Legal Considerations
While vegetable oil offers a renewable alternative, it’s not without hurdles:

• Cold Weather Performance
  Vegetable oil gels at higher temperatures than diesel, requiring heated systems.
  
• Fuel Tax Regulations
  In some regions, using untaxed fuel like WVO may attract legal scrutiny.
  
• Engine Warranty Limitations
  Manufacturers may void warranties if non-standard fuels are used.
  

Case Study: The Sunflower Experiment
A North Dakota farmer ran a tractor on sunflower oil sourced from a nearby crushing plant. The experiment lasted a summer, with no mechanical issues reported. The exhaust smelled like a roadside diner, and the novelty sparked local interest. Though not repeated, the trial demonstrated the viability of regionally sourced biofuels.
Conclusion: A Greasy Path Forward
Vegetable oil in heavy equipment diesels is not a one-size-fits-all solution, but it’s a compelling option for those willing to experiment. With proper filtration, heating, and engine selection, operators can tap into a renewable fuel source that’s been hiding in plain sight—on the shelf next to the olive oil. Whether driven by cost, sustainability, or curiosity, the journey from fryer to fuel tank continues to inspire innovation in the field.