Indian Oil Recruitment Notification for Engagement of Apprentices. Indian Oil Corporation Limited (IOCL), Refineries Division has published notification for the recruitment of Trade & Technician Apprentice Vacancies in Various Refinery. 101 – Trade Apprentice/Attendant Operator (Chemical Plant) Discipline – Chemical 102 – Trade Apprentice (Fitter) Discipline – Mechanical 103 – Trade Apprentice (Boiler) Discipline –