This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. Automotive Experiences 33 Automotive Experiences Vol. 3 No.1 (2020) pp. 33-38 Available online at http://journal.ummgl.ac.id/index.php/AutomotiveExperiences p-ISSN: 2615-6202 e-ISSN: 2615-6636 The Role of Eucalyptus Oil in Crude Palm Oil As Biodiesel Fuel Ena Marlina 1 , Mochammad Basjir 1 , Mitsuhisa Ichiyanagi 2 , Takashi Suzuki 2 , Gabriel Jeremy Gotama 3,4 , Willyanto Anggono 5,6 1 Department of Mechanical Engineering, Islamic University Malang 65145, East Java, Indonesia 2 Department of Engineering and Applied Sciences, Sophia University, Tokyo 102-8554, Japan 3 School of Mechanical and Aerospace Engineering, Nanyang Technological University, Nanyang 639798, Singapore 4 Department of Aerospace and Geodesy, Technical University of Munich, Taufkirchen/Ottobrunn 82024, Germany 5 Mechanical Engineering Department, Petra Christian University, Surabaya 60236, East Java , Indonesia 6 Centre for Sustainable Energy Studies, Petra Christian University, Surabaya 60236, East Java , Indonesia ena.marlina@unisma.ac.id https://doi.org/10.31603/ ae.v3i1.3257 Published by Automotive Laboratory of Universitas Muhammadiyah Magelang collaboration with Association of Indonesian Vocational Educators (AIVE) Abstract Article Info Submitted: 16/02/2020 Revised: 19/03/2020 Accepted: 23/03/2020 Utilization of crude palm oils (CPO) as biodiesel faces difficulty due to their high level of viscosity. Mixing crude eucalyptus oils (CEO) with CPO may reduce the viscosity due to the presence of aromatic compounds in CEO. The single droplet analysis was performed to determine the characteristics of mixing CPO with the CEO. The results showed that the addition of CEO decreased the viscosity due to the presence of intermolecular attractions, thereby leading to more active molecules in the CPO-CEO mixture. Furthermore, the aromatic compound in the CEO helped in decreasing the CPO flash point, while the aromatic compound in the triglyceride molecule weakens the bonds between molecules. The addition of CEO to CPO tends to reduce the ignition delay due to the presence of cineol content in the CEO, which weakens the van der Waals bond in CPO. Keywords: Eucalyptus oil, Crude palm oil, Biodiesel, Droplet Abstrak Minyak sawit (CPO) sebagai bahan bakar biodiesel memiliki viskositas yang tinggi, sehingga perlu penanganan untuk mengurangi viskositasnya. Perpaduan minyak kayu putih (CEO) dengan minyak sawit dapat menurunkan nilai viskositas minyak sawit karena adanya senyawa aromatik di dalam minyak kayu putih. Analisa tetesan (single droplet analysis) telah dilakukan untuk menentukan karakteristik campuran dari minyak sawit dengan minyak kayu putih. Penambahan minyak kayu putih menghasilkan penurunan viskositas karena interaksi antar molekul yang saling tarik-menarik. Interaksi ini menghasilkan pergerakan molekul yang lebih aktif pada campuran minyak sawit -minyak kayu putih. Penambahan minyak kayu putih menurunkan titik nyala bahan bakar. Senyawa aromatik dalam minyak kayu putih menjadi faktor utama yang membantu mengurangi nilai titik nyala pada minyak sawit; senyawa aromatik dalam molekul trigliserida menyebabkan ikatan antar molekul menjadi lemah. Penambahan minyak kayu putih pada minyak sawit menghasilkan pengurangan waktu tunda pengapian karena adanya senyawa Cineol pada minyak kayu putih yang melemahkan ikatan van der Waals dalam minyak sawit. Kata-kata kunci: Minyak kayu putih, Minyak sawit, Biodiesel, Droplet 1. Introduction Although considered as an alternative renewable fuel, the long-term use of vegetable oil may damage the engine due to its high viscosity. Mixing vegetable oil with other types of fuel is one of many solutions to reduce its viscosity [1].