1. Fuel (Gasoline): Provides the energy source for combustion.
2. Air: Necessary for combustion with the fuel.
3. Spark: Ignites the air-fuel mixture to create the explosion that drives the pistons.
4. Compression: The engine must compress the air-fuel mixture before ignition to increase the power of the explosion. This requires pistons and cylinders in good working order.
5. Lubrication: Oil is needed to reduce friction between moving parts, preventing damage and overheating.