Oil engine may refer to:

• Hornsby-Akroyd oil engine, the first internal combustion engine using heavy oil as fuel
• Crude oil engine, an internal combustion engine which can use many kinds of oil as fuel
• Oil burner (engine), a steam engine that uses oil as its fuel
• Hot bulb engine
• Hesselman engine
• Some forms of internal combustion engine, so called during an early period in their development

• Diesel engine