NOVELTY - Bio fuel composition for use as a source of energy for compression-ignition (C.I.) engine comprises 60-80% of diesel oil and 20-40% of essential oil, where the essential oil blended with diesel oil can decrease consumption of fuel such as for 15 kg load decrease of fuel is up to 0.00 to 0.221/hour.    USE - The bio fuel composition is useful as source of energy for C.I. engine (claimed) and for petrol and diesel engines.    ADVANTAGE - In the bio fuel composition, the essential oil blended with diesel oil in a dosage of 50 ml can mix in 10-20 liters/kg of fuel, so as to decrease the fuel consumption by 20%; or the essential oil blended with diesel oil in a dosage of 50 ml can mix in 10-20 liters/kg of fuel, so as to decrease the carbon emission by 40-50%, boost and increase energy/calorie power of fuel for better performance, help in smooth running and more purity of fuels, reduce noise and maintenance and maintains high performance level of present equipments (all claimed). The bio fuel composition provides an improvement in brake thermal efficiency. It is renewable and minimizes fossil fuel derived carbon dioxide emissions.    DETAILED DESCRIPTION - Bio fuel composition for use as a source of energy for compression-ignition (C.I.) engine comprises 60-80% of diesel oil and 20-40% of essential oil, where the essential oil blended with diesel oil can decrease consumption of fuel such as for 15 kg load decrease of fuel is up to 0.00 to 0.221/hour; or where the essential oil blended with diesel oil in a dosage of 50 ml can mix in 10-20 liters/kg of fuel, so as to decrease the fuel consumption by 20%; or where the essential oil blended with diesel oil in a dosage of 50 ml can mix in 10-20 liters/kg of fuel, so as to decrease the carbon emission by 40-50%, boost and increase energy/calorie power of fuel for better performance, help in smooth running and more purity of fuels, reduce noise and maintenance and maintains high performance level of present equipments; or bio fuel composition for use as a source of energy for C.I. engine, preferably selected from the following sources: Agar oil or oodh, distilled from Agarwood (Aquilaria malaccensis); Ajwain oil, distilled from the leaves of Bishop's weed (Carum copticum); Angelica root oil, distilled from Angelica archangelica; Anise oil, from Pimpinella anisum; Asafoetida; Balsam of Peru, from Myroxylon; Basil oil; Bay oil; Bergamot oil; black pepper essential oil is distilled from the berries of Piper nigrum; Buchu oil, made from the buchu shrub; Birch oils; Camphor; Cannabis flower essential oil; Caraway oil, Cardamom seed oil; Carrot seed oil (essential oil); Cedarwood oil, Chamomile oil; Calamus root; Cinnamon oil; Cistus species; Citronella oil; Clary Sage; Clove leaf oil; Coffee; Coriander; Costmary oil (bible leaf oil); Costus Root; Cranberry seed oil; Cubeb; Cumin oil/black seed oil; Cypress; Cypriol; Curry leaf; Davana oil; Dill oil, chemically almost identical to caraway seed oil; Elecampane, used medicinally; Eucalyptus oil; Fennel seed oil; Fenugreek oil; Fir; Frankincense oil; Galangal; Galbanum; Geranium oil; Ginger oil; Goldenrod; Grapefruit oil; Henna oil; Helichrysum; Hickory nut oil; Horseradish oil; Hyssop; Idaho Tansy; Jasmine oil; Juniper berry oil; Laurus nobilis; Lavender oil; Ledum; Lemon oil; Lemongrass; Lime; Litsea cubeba oil; Linaloe; Mandarin; Marjoram; Melaleuca See Tea tree oil; Melissa oil (Lemon balm); Mentha arvensis oil/Mint oil; Mountain Savory; Mugwort oil; Mustard oil; Myrrh oil; Myrtle; Neem oil or Neem Tree Oil; Neroli is produced from the blossom of the bitter orange tree; Nutmeg; Orange oil, like lemon oil; Oregano oil, contains thymol and carvacrol; Orris oil is extracted from the roots of the Florentine iris (Iris florentina); Palo Santo; Parsley oil; Patchouli oil; Perilla essential oil, extracted from the leaves of the perilla plant; Pennyroyal oil; Peppermint oil; Petitgrain; Pine oil; Ravensara; Red Cedar; Roman Chamomile; Rose oil; Rosehip oil, distilled from the seeds of the Rosa rubiginosa or Rosa mosqneta; Rosemary oil, distilled from the flowers of Rosmarinus officinalis; Rosewood oil; Sage oil; Sandalwood oil; Sassafras oil; Savory oil, from Satureja species; Schisandra oil, from Schisandra chinensis, used medicinally; Spearmint oil; Spikenard; Spruce; Star anise oil; Tangerine; Tarragon oil, distilled from Artemisia dracunculus; Tea tree oil, extracted from Melaleuca alternifolia, promoted for medicinal use, but with limited evidence of effectiveness; Thyme oil, used medicinally; Tsuga belongs to the pine tree family; Turmeric, used medicinally and to flavor food; Valerian; Vetiver oil (khus oil); Western red cedar; Wintergreen; Yarrow oil; Ylang-ylang; and Zedoary; where essential oil blended with diesel oil can decrease consumption of fuel by 20%. Full definitions are given in the DEFINITIONS (Full Definitions) Field.