Overview
Used Engine Oil (UEO) is a by-product collected after lubricating oils have been used in internal combustion engines, machinery, or industrial equipment. It contains a mixture of degraded base oil, combustion by-products, additives, heavy metals, and contaminants. Despite its degraded state, UEO remains a valuable industrial feedstock and is widely used in re-refining, fuel blending, and energy recovery applications.

Technical Characteristics

• Appearance: Dark brown to black viscous liquid
• Density @ 15°C: 0.90–0.95 g/cm³
• Viscosity @ 40°C: Highly variable (typically 50–150 cSt depending on degradation)
• Flash Point: 150–220°C (may vary)
• Water Content: ≤ 5% by volume (varies with collection process)
• Ash Content: 0.5–1.5%
• Sulfur Content: 0.5–1.5% by weight
• Contaminants (typical):
  • Heavy metals (Zn, Pb, Cu, Cr, Ni, Fe) from engine wear
  • Soot and carbonaceous matter
  • Additive residues (detergents, dispersants, anti-wear agents)
• Calorific Value: ~38–41 MJ/kg (~9,000–9,800 kcal/kg), similar to fuel oil

Specifications & Standards

• Composition depends on feedstock and collection methods
• Typically graded as:
  • Unfiltered UEO – raw collected oil with contaminants
  • Filtered UEO – screened to remove particulates and water
  • Re-refined Base Oil Feedstock – pretreated for re-refining processes
• Analyzed under ASTM and ISO testing methods: flash point, viscosity, water content, metals, and calorific value

Applications

• Fuel Blending: Substituted for heavy fuel oil (HFO) in industrial boilers, kilns, and furnaces
• Re-Refining: Feedstock for production of Group I & II base oils after vacuum distillation and hydrotreating
• Energy Recovery: Direct combustion in cement kilns, power plants, and marine engines (subject to environmental regulations)
• Industrial Uses: Raw material for lubricants, greases, and bitumen extenders after treatment

Performance Considerations

• High Calorific Value: Comparable to traditional heavy fuel oils, making it efficient for combustion
• Recyclability: Can be reprocessed into base oils, reducing dependence on crude-derived lubricants
• Environmental Impact: Requires treatment due to contaminants; uncontrolled use can cause pollution

Handling & Storage

• Store in sealed, steel tanks with secondary containment to prevent soil/water contamination
• Avoid mixing with solvents, coolants, or other waste streams to preserve re-refining value
• Must be handled in compliance with environmental and hazardous waste regulations
• Requires pretreatment (dehydration, filtration) before use as fuel or feedstock

Compliance & Testing

• Tested for viscosity (ASTM D445), flash point (ASTM D93), water content (ASTM D95), metals (ASTM D5185), sulfur (ASTM D4294), and calorific value (ASTM D240)
• Quality & Quantity (Q&Q) certification by independent inspectors (SGS, Intertek, CIQ) for bulk shipments

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